I use a pressue cooker because it is faster but you can just cook in a covered pan.
Heat oil in pan and add onion. Cook for 2 mins or until soft and add spices and cook for 1 min. Add lentils and stir through to flavour and then add tomato and stock. Cover and cook until lentils are soft. Remove from heat and add lemon juice and chopped corriander to taste. You can blend till smooth if desired or serve as is. Delicious!