Heat a grill pan or griddle over medium-high heat. Lightly rub the pineapple pieces with oil. Grill on all sides, about 2 minutes per side or until lightly caramelized with nice char marks. Remove from grill and set aside to cool slightly.
Cut grilled pineapple into 1/2-inch dice and add to a medium bowl. Add all remaining salsa ingredients, including the lime halves. These will lend the additional lime oils in the rinds to the mixture, making a more aromatic salsa. Set aside until ready to use.
While grill is still hot, rub each shark steak with olive oil and season with salt and pepper.
Place steaks on grill across the grill ribs and cook for about 3 to 5 minutes per side, depending on the thickness of the steaks. Gently turn fish so it does not fall apart. Once the flesh has become opaque and firm to the touch, it is cooked through. Remove to a platter and spoon salsa over fish. Serve immediately.