The Mixtures that are not allowed to be kneaded: 
A. First opinion:
Biblically: One only Biblically transgresses kneading with materials which are kneadable, such as flour or earth used for bricks of a building. However ash and course sand and crushed grain and parched flour and the like are not kneadable materials, and thus one who kneads them does not transgress a Biblical prohibition.
Rabbinically-Roasted flour: It is Rabinically forbidden to knead a lot of roasted flour [into a thick batter], as this may lead one to come to knead non-roasted flour and he will transgress a Biblical prohibition.
However one is allowed to knead the roasted flour little by little as this is considered a change from the way it is normally done during the week [and one will thus not come to forget and also knead regular flour]. (Furthermore even if he kneads it into a thick and course mixture and thus appears like kneading [nevertheless] it is permitted being that he is kneading with an irregularity.)
Thick flour/Shesisa: Grains which have not yet grown a third [of their growth] and have been roasted, and then ground thickly, having structure like sand, and is called shetisa, may be kneaded with vinegar and the like even a lot at a time so long as one kneads it into a thin batter.
However [to knead it into] a thick batter is forbidden [to do a lot at a time even if one does it with an irregularity] as it appears like kneading. (However if kneaded a little at a time it is permitted [to be made even into a thick batter] as was explained by roasted [flour]).
A thin batter: Even [when kneading] a thin batter, when making a lot at a time one must do so slightly differently than the way it is normally done.
The definition of a “different way than usual”: See Halacha 3
B. The second opinion:
There are those which argue on the above and hold that:
Biblically: There is no difference between materials which are kneadable and materials which are not kneadable, and by all the materials one is Biblically liable by simply placing water into them or one of the other liquids and fruits juices [when making a thick batter as will be explained below].
Rabinically Forbidden and Totally permitted: Rabinically [even a thin batter is forbidden from being made] unless it is done differently than the way it is normally done as was explained above, in which case the sages permitted it to be done if it is needed on Shabbos, whether the material is kneadable and whether the material is not kneadable.
Thus both roasted flour and Shesisa are forbidden to have liquid placed in them on Shabbos even if one does so in a different way than is normally done, unless it is made into a thin batter in which case it may be done in a different way than normal, such as to first places the flour/shesisa in the bowl and then place the vinegar in an area that this is different than usual, or the opposite in a place that the opposite is considered a different way [as will be explained in Halacha 3].
Kneading a lot at a time: When placing the [material] in an irregular way it is permitted to knead even a lot at a time being that it is being made into a thin batter. However to make a thick batter is forbidden in all circumstances due to that it is considered kneading.
C. The Final Ruling:
The remainder of the above quoted Halacha was lost from the text. The following is the Final Ruling of Admur in Chapter 324 Halacha 3
The Final Ruling: One should be stringent like the second opinion, and so is the custom [to not place water into even un-knead able material in a way that if mixed will knead into a thick mixture, even with an irregularity. Although to make a thin batter is permitted to make even with kneadable materials as long as one does so with an irregularity.]
Summary-Placing water into food/material on Shabbos:
First Opinion: Some opinions rule that Biblical kneading only applies by kneadable materials like flour or cement. Non-kneadable materials are only Rabinically prohibited, and if done with an irregularity, which is defined as kneading a little at a time, it is allowed to be made even into a thick mixture.
Furthermore they rule it only applies when one actually kneads the kneadable material with liquid, and does not apply when merely placing water into it without kneading it.
Second Opinion: Others rule that Biblical kneading applies by all materials, even un-kneadable, and even if one just places water in it without actually kneading.
Thin batters: According to all kneading is only Biblically prohibited when the mixture is made into a thick mixture. If made into a thin batter, it is only Rabinically prohibited and if done with an irregularity it is permitted to be done even a lot at a time.
- The Final Ruling:
We are stringent like the latter opinion and thus one may only knead liquid with material [whether knead able or not] into a thin batter and only with an irregularity. As well one may not even simply place water into a mixture, even if he does not plan to mix it, if this will create a thick batter.
Regarding adding more water to an already kneaded food-See Q&A below!
Regarding the definition of an “irregularity”- See Halacha 4
Are we also stringent like the first opinion in cases that there is a kneading prohibition only according to their opinion?
Yes. We are stringent like both opinions. For an example of a case where the first opinion is strict over the second opinion- See Halacha 5 Q&A, and footnote there!
When permitted to knead, must one do so right before the meal?
What is the definition of a thin mixture?
This matter is debated amongst the Poskim. Seemingly making a mixture thinner [i.e. more watery] then it usually is made, is considered a thin mixture and may be done with an irregularity.
If the mixture is made so thin that it can be drunk then according to all this would be considered a thin mixture and does not even contain the concept of kneading, unless this is the normal way that the mixture is made, such as regarding cement.
When making a thin mixture must one place all the liquid into the food simultaneously or may one place it in a little at a time? 
One must place all the liquid in simultaneously.
If mixing liquid into a food before Shabbos will ruin that food is there room to be lenient like the first opinion to make it into a thick mixture on Shabbos?
If doing so before Shabbos would ruin the food, or make it less appetizing, than one may be lenient like the first opinion mentioned above which allows kneading into a thick mixture, with an irregularity foods which are not knead-able, such as bananas and radishes. Foods which are kneadable are forbidden to be kneaded according to all. [In all cases where one cannot knead the mixture before Shabbos it is preferable to place the liquid in the food from before Shabbos without kneading it, and then knead it on Shabbos. If however this too will ruin the food then one may do as stated above.]
If one forgot to knead a food before Shabbos may he be lenient like the first opinion mentioned to make a thick mixture using an irregularity?
No. See footnote.
When making a drink using dissolvable powders must one do so with an irregularity?
If the powder will dissolve immediately upon adding the liquid to it, it is allowed to be made without any irregularities. [However according to some doing so would involve a Nolad prohibition, and thus although one is allowed to be lenient, it is proper if possible to prepare this mixture from before Shabbos.]
However if the powder will not dissolve right away then if it will become a semi thick mixture in the interim of it dissolving into the liquid, it may only be made with the mentioned irregularities.
May one make a protein shake?
There are many recipes for protein shakes, and hence the Halacha would depend on the type of shake one is making. One may not make the shake into a thick batter if using oatmeal or other grain, and must do so with the mentioned irregularities when making it into a thin batter. When using a thick liquid, such as honey, syrup, eggs, thick whey protein and the like one is to avoid mixing the liquids together very quickly.
If the adding of liquid to a certain food will at first thicken it and only after further mixing of water will it thin it out, may one make it into a thin mixture on Shabbos?
No. Thus one may not make Techina on Shabbos into a thick mixture even if he plans to eventually thin it out with more liquid as nevertheless in the interim it thickens due to the liquids added.
Ketzos Hashulchan 130/2. However when kneading it to a thin mixture it is allowed, as stated in the second opinion below.
 The M”B  however rules that by roasted flour one may knead it little by little being that he holds that we do not apply the kneading prohibition by cooked foods. See Halacha 5 Q&A there!
 Based on Ketzos Hashulchan 130/2
 Ketzos Hashulchan 130 footnote 1
 Mishneh Berurah  in name of Magen Avraham, and so is implied from Admur that states that one may do even a lot at a time.
 As according to the Rashba adding liquid to a food on Shabbos contains the “Make Bipatish/Finishing Touch” prohibition unless done right before the meal. See Ketzos Hashulchan 130 footnote 12
 Ketzos Hashulchan 130 footnote 3
 Some Poskim hold that it is only considered a thick mixture if made as thick as dough, while anything less than this is considered a thin mixture. So seems to be the ruling of Chazon Ish which rules that the definition of a thin mixture is so long as it is thick and flowy, thus implying that a thick mixture is when it is so thick that it does not flow. Other Poskim rule that it must be as thin as water to be considered a thin mixture. See Ketzos Hashulchan there!
 So rules also Chazon Ish 58/9
 Ketzos Hashulchan 130 footnote 4, SSH”K 8/9
 As otherwise during the interval of which only some of the liquid has been placed the mixture is considered a thick mixture which is forbidden to be done.
 Ketzos Hashulchan 130/6 footnote 19, and SSH”K 8/11. Vetzaruch Iyun Gadol that the SSH”K does not limit this allowance only to a case that the mixture is of a non-knead-able substance!
 Regarding the type of irregularity required, Admur brings in the first opinion that when one makes the thick batter of un-kneadable material a little at a time it is considered an irregularity. Later when he mentions kneading a thin batter he mentions the changes of the order of which food to enter, and changing in the mixing method. Vetzaruch Iyun regarding the difference of these two forms of irregularities and as in truth which irregularity should be used when being lenient to make a thick batter. In SSH”K ibid they mention doing the latter irregularity which is ruled to do for a thin batter. See Igros Moshe 4/74 Lash for a summary of the different forms of irregularities.
 As in this case it would be allowed according to all as will be explained in Halacha 5 –See summary there!
 SSH”K 8/10
 If the mixture is a kneadable substance this is forbidden according to all. If the mixture is not a kneadable substance then Tzaruch Iyun, as on the one hand why should this be any different than the previous Q&A of which we allow to knead on Shabbos if it could not have been done before Shabbos. On the other hand from Admur this does not seem to be the case, as Admur rules that the custom is to be stringent like the second opinion, as well as that regarding Charoses 473/34, as learns Ketzos Hashulchan [See Halacha 6] and M”B, one may only make the Charoses into a thin batter, and there it is discussing that one forgot to do so before Shabbos. Vetzaruch Iyun Gadol on SSH”K [8/11] which rules that even a thick batter may be made with an irregularity if one forgot to do so before Shabbos, and footnotes to the M”B regarding Charoses when the M”B himself rules as stated above that one may only be lenient to make it into a thin batter!
 SSH”K 8/18
 As rules Rav Farkash with regards to instant coffee. See The laws of cooking Halacha 12 Q&A there!
 SSH”K 8/26