Buy the fish cleaned, scaled and with the head removed.
Wipe out cavity with kitchen paper dipped in coarse salt and wash well.
Rub inside cavity with a little salt and lemon juice.
Heat oil and gently fry ginger, garlic and chili until soft.
Add cumin and garam masala and fry for 2-3 minutes.
Remove from heat, stir into yoghurt and add salt to taste.
Dry fish on paper towel, make diagonal slits in the flesh on each side and put into a greased baking dish.
Spread the marinade on both sides of the fish and inside the cavity.
Leave to stand at room temperature for 30 minutes.
Then bake in a moderate oven 35 minutes or until flesh is white and opaque at the thickest portion.
Garnish with coriander leaves and chili.