Heat the oil in a large frying pan or wok on the hob and fry the onions for about 8 minutes until beginning to brown. Stir in the ginger, garlic, cumin and coriander seeds, chilli flakes, cloves and cinnamon, and cook for a further 2 minutes.
Pour in the stock and add the lime juice, sugar, soy sauce and green pepper. Bring almost to the boil. Pour the contents of the pan into a casserole dish and cover with foil. Place on the lower rack of the halogen oven. Set the temperature to 225°C (437°F) and cook for 15 minutes.
Meanwhile, blend the cornflour with 4 tablespoons of the reserved pineapple juice in a small bowl. Chop the pineapple slices and add to the casserole along with the cornflour mixture and the prawns. Cook, uncovered, for a further 10 minutes or until the sauce has thickened and the prawns are pink and cooked through. Serve with steamed rice or sesame noodles.