Preheat the oven to 180°C.
Melt the butter in a large lidded dish and sizzle the garam masala for a moment.
Stir in the rice until the grains are coated in the spiced butter.
Add bay leaf, lemon zest, chilli, ginger, salt, and pepper.
Pour in 375ml of stock and bring it to a simmer.
Lay the fish on top, submerge it slightly, cover, and bake for 15 to 20 minutes.
Remove from the oven and let it stand covered for 5 to 7 minutes.
Remove the skin from the fish and add the egg, onions, and coriander.
Flake the fish and mix everything gently with two forks while removing the bay leaf.
Cover with a tea towel and lid for 5 minutes to absorb excess steam.
Mix again lightly and serve on hot plates with a squeeze of lemon juice.