Stir fry is one of my big go-tos. All you need is a pan and spatula or tongs, whatever veg you have on hand, oil, salt. You can mix in seasonings but honestly if cooked well I don’t find it to be that necessary. Fried rice or rice stuff is in a similar vein. Cook whatever random stuff you have around, remove from the pan, start frying the rice, throw in an egg, add it all back into the pan briefly.
Street tacos are baller and you can put all kinds of things in them and make them work with just about any dietary restrictions. I prefer to go heavy handed with the seasoning but you can make it work with only a couple spices. Best with two pans, one to heat up the tortillas. Making pico de gallo is good knife skill practice and extra can the thrown on nachos directly or quickly turned into salsa.
All the soup and then some seriously there are so many great soup recipes and tricks. I love egg drop because it can be as simple as broth and an egg, though usually I put in some frozen veg and thicken with corn starch. If you eat meat and have these in your area, you can grab one of those hot held roast chickens for cheap. Lazily process it, throw all the bones and whatever is stuck to them into a pot and make a quick and cheap stock. Plus now there is a bunch of chicken laying around ready to be a chicken noodle or chicken tortilla soup.
If your stove has an oven: Ratatouille is surprisingly easy to make, costs basically nothing, and can be done in an oven or a slow cooker. Jalapeno poppers can also be weirdly cheap and easy to make. Really anything where a main component is a veg and you put it in the oven. Roast broccoli only needs oil and salt to come out great.
I like to make savory oatmeal and have pre-measured containers for breakfast prep. Oats, salt, pepper, brewers yeast. Just add water. I mix in cream cheese and put a fried egg on top. It’s cheap and filling and you can really push what you’re adding to them and at worse still come out with something okay enough.
I hope these are the kinds of things you’re looking for and they get some ideas going. If you have questions about anything or need inspiration let me know! I’ve been living with a chef for a lot of years and have a decent bit of knowledge I can share