Place the salmon fillets in the freezer for about 30 or 40 minutes to firm up slightly. Remove and discard the skin, then use a sharp knife to cut the fish into 1 inch cubes, removing any stray bones.

Pour the vegetable stock into a pan and slowly boil. Add shallots, garlic, ginger, lemon grass, chili flakes, fish sauce and brown sugar. Bring back to boil. Stir well to ensure the ingredients are thoroughly mixed and reduce the heat, simmer gently for 15 minutes.

Add the fish pieces, bring back to a boil, then turn off the heat. Leave the curry to stand for 10-15 minutes, then serve in small bowls with bread or rice.