Soak the lentils for between 4 and 8 hours in boiling water. When ready to cook rinse the lentils in warm water and drain.
Heat the oil in a medium pan, add the cumin seeds and cook for about a minute or until browned.
Remove the pan from the heat and add garlic, ginger and chillies. Stir this very quickly, as you don't want it to burn, add lentils, turmeric, salt and 300ml/10fl oz of warm water. Bring to the boil, cover and cook for 10 minutes on a gentle simmer. Do not let the water reduce by more than a third of the original quantity, if it does add more warm water.
Check that the lentils are cooked, by scooping out a few with a spoon and crushing them between your fingers. You should only have to apply a little pressure for the lentil to squash, once cooked add all the vegetables and 100ml/3½fl oz of warm water.
Stir and check seasoning, cover and cook for 5 minutes on a medium heat stirring occasionally. The vegetables should still have a little crunch to them when the dish is cooked, serve and sprinkle with chopped tomatoes and coriander.