Cook rice or pasta, they're super cheap. and have some (small amount of) salty side dish.
Choose unmilled rice or brown pasta so you would get more nutrients.
Buy tea bags and put in a big jug, keep it in a fridge.
ive been doing this daily and now im 26, saved tons of money for something fun and still healthy.
Dont forget beans. U can base a whole meal off of red beans and rice or butter beans and cornbread... Stuff like that. Or focus on a main course like chicken and dumplings, chicken and rice or beef tips over pasta. These dont even require sides and give plenty leftovers! (Mom of 3 lol)
I do mean super cheap like about $30 a week but not unhealthy and pretty simple for one person.