rice
canned kidney beans (you need a good amount of beans to rice to get a complete protein profile)
vegetable stock (i use powdered which seems cheapest)
ground coriander seeds
ground cumin
ground chipotle or any chili
limes or vinegar
shallots or onions, hot chili (if you like it hotter)
garlic and or garlic powder
tomato paste
any oil
salt, pepper
fresh coriander and parsley if you can afford it (i use frozen parsley)

a large pan or pot with airtight lid (this is necessary to steam the rice)

drain beans
wash rice if you are concerned about arsenic or dirt (i sometimes leave it dry to get a bit of toast on the rice)
make about 0.5L of vegetable broth
chop onions and garlic, chop chili (de-seed for less heat)
heat pan with oil, add powdered spices (not the garlic powder) until fragrant,
add onions and garlic, chili, stir as needed
add tomato paste (about 1 tablespoon)
after about a minute add rice (stir until a bit toasted)
add beans, stir
cover with broth (about 0.5 - 1 cm above rice) add water if necessary
add parsley, garlic powder, salt, pepper, dash of vinegar (if not using limes)
cover pan, turn heat to lowest (if that burns on the bottom you can also turn off heat)
cook 20-25 minutes (do not open the lid)
near the end roughly chop fresh coriander
turn off heat, open lid, gently stir
close lid and let it sit for 5 minutes (not strictly necessary, YMMV)
if you like it tangy add some more vinegar to taste, add salt if necessary
serve with limes and fresh parsley

a very cheap meal that can be upgraded (fresh coriander, limes) if you have some money left over.

for non-vegetarian experiment with lard instead of oil and chicken stock.