A lot of food history is making the best out of what you got and when you look around there are some incredible depression era and post war dishes from all over the world.
Like it can be amazing what you can make with basic ingredients that can taste good that some ancestor from a different world figured out with what scraps they had laying around. A bunch of my favorite dishes are like that. Okonomiyaki especially so.









Oh shoot also, you said vegetarian so I didnt include this but you could probably make it work.
Okonomiyaki:
Its practically fish flavored pancake batter filled with cabbage and other veggies fried on a griddle. Invented in japan after WW2 to use scraps and make them tasty.
I make mine with bacon or cheap slices of ham on bottom but you can skip that, but I would still crack an egg into the center.
If you look around at street food post WW2 in the world you will find a lot of it is cheap and tasty and with a globalized market easier to get the ingredients/recipes.