Heat the oil and butter in a small frying pan. Add the onion and garlic and fry for 2–3 minutes until softened. Stir in the spice mix and cinnamon stick and fry for a further minute. Add the tomatoes, crème fraîche, lime rind and juice and heat for a minute.
Put the salmon in an ovenproof dish. Spoon over the sauce, cover the dish tightly with foil and cook in a preheated oven, 200°C (400°F), Gas Mark 6, for 15–20 minutes or until the salmon is just cooked.
Meanwhile, make the salad by tossing together the tomatoes, onion and coriander. Dress with lemon juice.
Serve the salmon with basmati rice and the tomato and onion salad.