I have noticed that many cultures have some kind of grain + legume dish in their diets, some relatively new and some very old. This combination gives you all the human dietary essential amino acids from (cheap) plant sources. For example:
- Beans on toast (UK)
- Hummus & pita (Middle East)
- Doubles - chickpea curry & fried bread (Trinidad)
- Red beans & rice (Cajun)
- Black beans over rice (South/Central America)
- Rice & dal (India)
- Paan & parippu - bread and lentil curry (Sri Lanka)
- Koshary - rice, pasta & lentils (Egypt)
- Pasta e fagioli - pasta & beans (Italy)