For the paint:
1 1/2 tablespoons of whole black peppercorns
12 whole cloves
1/2 cup sugar
3/4 cup low-sodium soy sauce
3/4 cup light rum
2 1/2 tablespoons of grated lemon zest
2 tablespoons lemon juice

For the fish:
4, 8-ounce portions of boneless, skinless fillet of grouper
1 tablespoon peanut oil for cooking the fish

For the mangoes:
1 ripe, juicy mango, peeled and thinly sliced into wedges

For the paint: Toast the black peppercorns and cloves together in a dry
skillet over moderate heat until you see a puff or two of smoke. Remove
from the heat and grind them together in an electric spice grinder or a
clean coffee bean grinder. Transfer peppercorns to a heavy saucepan. Add
the remaining ingredients and heat all together on medium heat. The
mixture will begin to foam as it reduces. When it has reduced by
approximately half, about 25 to 35 minutes, strain it through a
fine-meshed strainer into a bowl. Reserve until needed.

Note: The rum can suddenly ignite. If it does, cover the pan to kill
off the oxygen. Resume heating and reducing as before.

For the fish: Just before serving the dish, preheat an oven to 450 F.
Place the fish on a large platter and then paint the fish liberally on one
side only. Heat a large skillet (or two of them) until almost smoking hot.
Add some peanut oil and carefully add the fish, paint-side down. Shake the
pan to avoid sticking. When the fish is quite dark, flip it over, degrease
any excess oil and place the skillet in the oven. Bake the fish until just
cooked through. Lay the mangoes over the fish evenly. Serve with a wedge
of lemon or lime.