Delicious beef curry

SERVES SIX

4 Tbsp sunflower oil1 large onion, finely sliced1 Tbsp crushed garlic and2 red chillies, thinly sliced1 Tbsp garam masala1 tsp ground coriander2 tsp ground cumin1 tsp chilli powder2 tsp turmeric800g stewing beef, cut into pieces1 brinjal, diced1 can chopped tomatoes1 sachet tomato paste1 can coconut milkSalt and pepper, to tasteFresh coriander leaves, to serve