Cut salmon into bite sized pieces, leave to one side. Coat a medium sized saucepan with cooking spray, saute shallots and garlic for 30 seconds. Combine cornflour with evaporated milk, add to pan, stir continuously until boiled. Reduce heat, add salmon, capers, cream cheese and fish sauce, stir until cheese has melted. Pepper to taste. Lower heat and keep hot while fish is cooking. Generously coat a non stick frying pan with cooking spray, fry fish fillets for 2 to 3 minutes each side until just cooked and browned(turn only once to avoid drying out fish). Place fish on serving plates and pour sauce over the top.