Finding a cheaper lunch routine that does not rely on eating the same leftovers daily

A packed lunch saves money until I get bored of the same rice and chicken by Wednesday and buy something out. I'm trying to build a rotation from a handful of cheap components: wraps, beans, boiled eggs, roasted vegetables, sauces and whatever fruit is affordable. Ideally assembly takes five minutes in the morning. What lunches stay appealing for four workdays without requiring a heroic Sunday meal-prep session? Please don't suggest five identical tubs.