Relish:
2 cups diced fresh pineapple
1 to 2 chile peppers, seeded and minced
1 cup white wine vinegar
2 cloves garlic, minced
2 tablespoons brown sugar
1 tablespoon soy sauce
Tuna:
1 tablespoon black peppercorns, crushed
4 tuna steaks, about 8 ounces each
1 lemon, quartered
2 tablespoons peanut oil
To make the relish, combine pineapple, chile peppers, vinegar, garlic, brown sugar and soy sauce in a wok. Cook over medium heat for 15 to 20 minutes, stirring occasionally. Drain the mixture and discard liquid. Transfer the relish to a serving bowl and refrigerate.
To prepare the fish, press the peppercorns into the tuna steaks. Squeeze the lemon over the tuna. Pour the oil into the wok and heat until barely smoking. Place tuna steaks in the wok and cook for 5 to 7 minutes, then turn. Continue until cooked in the center. Transfer fish to warm plates. Spoon relish over the hot tuna steaks and serve.