Fry the mustard seeds in a little oil until they pop. Add the cumin seeds, cardamon and curry leaves and stir in a medium heat for a few minutes. Chop the onion and cook until browned (ideally covered with a lid and cooked on a low heat). Grate or chop the garlic and add to the pan and cook for a couple of minutes. Add the turmeric and chilli powder. Prick the green chillis and add to the pan. Chop the tomatoes and add a little oil or splash of water if required.

Wash the lentils well and cook according to instructions in plenty of water. These can be cooking at the same time as the spice mixture if you wish. When the lentils reach the boil, remove the foam as this will make the dahl bitter. When the lentils are cooked there should be around 2 inches of water in the pan above the lentils.

Add the lentils to the spice mixture (it helps if this is hot and sizzling) and gently whisk together. Continue to cook for another 10 minutes. The mixture will thicken but you can add more water if you wish.

The whole spices tend to float to the top so you can remove them if you prefer (remove if you are giving to a child or anyone that might choke) but I like to leave them in. Add the lemon juice of a small lemon and chopped coriander to taste.