Cook your choice of something like rice, Quinoa or barely. Maybe dice half an onion and toss it in as well. Bonus points for switching 1/4 of the water for veg stock. When it's done cooking, through in some canned beans and hot sauce. Mix. Serve in tortillas as a taco. Bonus points for grated cheese, salsa, and/or avocado in the taco as well.

One pan. Lots of protein and fiber. $4 for multiple meals.

Curry curry curry. I'll make a big batch of lentil or bean curry using lots of onions and whatever tomatoes are about to go (or were bought and found out to be watery, tasteless sad bois). A lil tempered whole spices, some garam masala, onions, tomatoes (and or peppers), cooked well with most any legume in a pressure cooker, makes a huge amount of healthy tasty food cheaply. I'll thicken it with shredded coconut and toss in fresh herbs or dried methi.

Lunch for 2 weeks, just add fresh rice. I'll freeze half and thaw for the following week or another if I'm craving more variety.

Edit: if you're not buying your spices at an Indian grocery and you have access to one, you're drastically overspending on spices. I buy 250g of whole cumin for under $2. That'll cost you five fold that from McCormick's or what have you.

Edit2: of course meat curries are possible, too. They cost a lil more, but still a great way to stretch your dollars while eating healthy and deliciously.

This is a little dependant on the definition of healthy, but I see carbs as a little bit of poison, so my go to meal is always omlette au fromage. I roll it into a sort of wrap while it's on the pan, but other than that I do nothing special.

Not a direct answer to your question, but soup makers are a fun and very, very easy way to eat healthily and cheaply. I got mine from a charity store for £5 but they're available new for under £50. You literally just throw in your ingredients, a bit of water and press go. Thirty minutes later: thick, tasty, piping hot soup. It's a really good way of using veg that's reduced at the supermarket.

Brocoli pasta or rice salads really hit the spot Anything pasta really

If you spread it out over several meals, ramen is totally doable and affordable from scratch.

Look up the PDF by ramen lord, I also have a comic like ramen book that's great

Edit: I tend to make a batch of broths and freeze them. Lasts several meals that way. (For a family).

Second edit: the other book is "Let's make ramen" and it's great.