Heat the oil in a large frying pan over a medium heat. Add the garlic, ginger, onion and chillies and stir-fry for 6–8 minutes until the onion is lightly golden. Add the chilli powder, cumin, ground coriander, yogurt, tomato purée and garam masala. Stir-fry for a further 1–2 minutes.
Add the measured water and bring to the boil. Add the tamarind paste, curry powder, red pepper and chickpeas, and bring back to the boil. Season to taste, reduce the heat to low and simmer gently for 25–30 minutes until the sauce is thick and rich.
Divide between 4 small serving bowls, drizzle with extra yogurt and garnish with chopped coriander. Serve with lemon wedges on the side.