Parboil your cubed potato until almost cooked through. Then add the rest of the vegetables and simmer them with the potato until just cooked through but still quite fresh looking. Drain and set aside.
To make the korma paste, lightly toast the chana lentils in a dry frying pan until light brown, 11⁄2–2 minutes, then transfer to a plate to cool. Roast the cumin and coriander seeds in the same way. They are ready when fragrant. If they begin to smoke, get them off the heat.
Place the lentils, cumin seeds and coriander seeds in a spice grinder with the other paste ingredients and grind to a smooth, thick paste.
When you’re ready to make the curry, soak the saffron in 3 tablespoons of warm milk (if using) and set aside. Heat the ghee, butter or oil in a large saucepan that has a lid. When visibly hot, add the cinnamon stick and cardamom pods and temper these spices in the oil for about 30 seconds before adding the curry leaves. Temper the leaves for another 30 seconds, then add the chopped onions. Fry the onions until soft and lightly browned, about 5 minutes, and then stir in the garlic and ginger paste.
Add the chopped tomatoes and turmeric and let this mixture all cook for another couple of minutes before adding your prepared korma paste. Toss in the par-cooked vegetables and about 250ml (1 cup) water to cover. Stir well and place the lid on the top. Cook, covered, for a couple of minutes, until the sauce has thickened and the vegetables are fully cooked. If you prefer a thicker sauce, remove the pan lid for a minute or until you are happy with the consistency.
Pour in the cream or yoghurt and the saffron-infused milk (if using) and cook for another 1 minute with the lid on.
To finish, season with salt to taste, garnish with the coriander and sprinkle the garam masala over the top and, if you like, toasted chopped cashew nuts.
Extracted from The Curry Guy Veggie by Dan Toombs, Quadrille, £15
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