First I create a bed of taste by stewing flavorful vegetables that work best with the basic protein and the other ingredients.
Onions or other members of the onion family, carrots, and celery are sure-fire neutral flavors that work with everything. Bell peppers, tomatoes, and mushrooms form the second tier of seasoning vegetables. They’re more aromatic and distinctive than onions and carrots and dominate other tastes; use them only if you like their unique flavors.
I consider the vegetables listed above “foundation flavors” because they work well with a huge variety of other tastes, can be cooked in advance, and their flavors remain constant even with reheating.