Cooking from scratch is the single biggest lever most households have for eating well on less. You do not need to be a chef. You need a small handful of skills that you use over and over.
Knife skills come first. A sharp knife and the ability to chop an onion safely transforms cooking from a chore into a rhythm.
Cooking rice is the second. A pot of rice plus almost anything else equals dinner. Two cups of water, one cup of rice, a pinch of salt, simmered covered for eighteen minutes.
Eggs are the third. Scrambled, fried, hard-boiled, or as a frittata, eggs are a complete protein at a low price.
Soup is the fourth. Onion, broth, vegetables, and a starch produce dinner from almost any combination.
Bread is the fifth. A simple loaf takes ten minutes of active work and turns a few cents of flour into something that warms a whole house.