Flavor does not matter, presentation does not matter but the food shouldn’t make you sick, and should ideally have enough calories per day for the average person to survive (2000 kcal min).
Edit: I am not in any danger of starving or malnutrition, nor am I insolvent. I’m mainly asking this question out of curiosity on how people would approach a solution :)
Had to upvote because you’re entirely correct. Protein deficiency isn’t really a thing in the developed world, except for those who are eating exceptionally poorly. There is one amino acid that is absent or very low in most legumes, but it can be found in most grains or nuts, so the slightest effort can remove the risk of deficiency.
Most nutritional diseases in the developed world are due to excess, not deficiency.