Heat the oil in a large pot over medium heat. Add the onion, leeks, chili and garlic, and stir-fry for 10 minutes.
Add the chickpeas and vegetable stock, and bring to a boil. Reduce heat to medium-low, partially cover and simmer for 40 minutes. Add the barley, lentils, salt and pepper and bring back to a boil. Reduce heat to simmer, partially cover and cook for