> Do you have any examples of products that are meant to be a meal replacement, and that contain all necessary nutrients?
The tube feeds [0] are pretty much exactly that. Those Fresenius ones are not flavored but other manufacturers, like HiPP/Abbot, even have flavored tube feed, as some tube patients like having the flavor come up when they have to burp.
A step closer are the "nutritional supplements", which is a weird name for it in German we call it "Trinknahrung" which literally translates to "liquid nutrition".
These are usually flavored and come in a variety of forms, like powder or even puddings.
I've "eaten" the stuff sometimes for diet or after tooth operations, it's pretty okayish when cold, like a milkshake. The biggest issue is that you have to be really careful about how fast you drink it until your digestive system adapted to the high-calorie contents, as drinking too much too fast will also make it come out too fast, so to speak.
[0] http://www.fresenius-kabi.co.uk/4347.htm
