A few people already keyed in on this but just to make it abundantly clear:
“Peasant food”.
So that means:
Whatever meat/protein and veg is on sale. Don’t neglect the frozen food aisle. Most (all?) of that is flash frozen and, honestly, fresher than if you were to buy it in the produce section. Some veg handles this better than other (frozen spinach makes me vomit, Frozen peas are amazing) but it is cheap and nutritious
Something cheap as filler (I grew up with rice so I eat a lot of rice)
Whatever spice is cheap. You can never go wrong with buying the big bag of mexican seasoning at the supermarket. Usually cheap because “mexican” and usually has a good blend that comes in a range of spice levels. Just taste it to get a feel for how much salt is in there so you can add salt accordingly while cooking.
Cook the filler as you would. Oven or pan the protein. Season generously.
Cooking shows/youtube make us think this is a lot more complicated than it really is. But if you learn a few basic cooking techniques (“stir fry” is love, “stir fry” is life) then you are basically set and can be That Guy who stands in the aisle at the supermarket figuring out what he is making next week based on what is available.