Heat a sturdy and dry pan over a low heat and toast the lentils, peppercorns, mustard, coriander, cumin, fennel and fenugreek seeds for 3-4 mins, stirring all the time, until they release a nutty and earthy aroma. Turn off the heat and stir in the cinnamon, chilli powder, turmeric, ginger and dried curry leaves, if using.

Leave to cool and then pound the lentils and spices to a powder with a pestle and mortar, or you can use an electric grinder. Store in an airtight jar or keep the curry powder in a sealed bag in the freezer. It will stay fresh, at room temperature, for 2 months or 6 months in the freezer.