Soak the lentils for at least 2 hrs or overnight. Rinse them and put in a pan with 1 litre of cold water and the baking soda. Bring to the boil, remove the arising foam until the surface is clear, then mix in the turmeric.

Bubble gently for 20 mins until you can squash a lentil between your fingers easily. Add the tomatoes and the spinach. Cook for another 15 mins, stirring regularly and mashing the lentils against the side of the saucepan to thicken the dal. Add a splash of hot water, if it's getting a little dry. Mix in salt to taste. Will keep frozen for up to three months, see tip.

Then, make the tadka. In a small pan, melt the ghee over a medium-high heat until it melts. Add the red chillies and sizzle for a few seconds, then add the cumin seeds, garlic and chilli powder. You’ll need to work quickly so the spices don’t burn. Turn off the heat and pour the tadka over the cooked lentils. My granny’s tip is to spoon a little dal back into the pan to nab any tadka left behind, before tipping it back into the dish. Serve with warm naans.