Wash lentils in several changes of water and check for any small stones. Drain. No need to soak.
Heat the olive oil in a medium-sized saucepan over moderate heat, add the diced onion and green pepper and fry gently until softened, about 5 minutes. Add in minced garlic and cumin and ginger and fry for another few minutes to release the aroma, stirring continuously.
Add drained lentils, dates, hot vegetable stock and tomatoes. Bring to the boil, reduce heat, cover and simmer over low heat for 15 minutes.
Season to taste and simmer uncovered for another 5 minutes. The stew is ready when the lentils are soft and liquid has almost evaporated.
To serve, place a portion of the quinoa or rice into a bowl, top with lentil stew and garnish with yoghurt with chopped mint as desired.