Creamy spiced potato and spinach curry

Method

1. Parboil the potatoes in salted boiling water for 8-10 minutes until just tender. Drain, then prick with a fork to roughen the edges.
2. Heat the oil in a large sauté pan over a medium heat. Add the onion and a pinch of salt, then cook for 15 minutes, stirring, until golden. Add the garlic and spices, then cook, stirring, for 1 minute. Add the butter and potatoes, then stir to coat. Cook for 10 minutes, stirring occasionally so the spices don’t catch and burn.
3. Spoon the yogurt into a bowl, add the ginger, then season. Stir into the pan with a splash of water and heat gently for 5 minutes until the potatoes are tender and the sauce
4. is thickened. Season to taste.
5. Put the spinach in a colander and pour freshly boiled water over it, then refresh under cold water and squeeze dry. Stir through the curry.
6. Scatter with the mint and chilli, then serve with lemon wedges.