Thread one shrimp and one scallop onto small, sturdy skewers about 9cm (3½in) long - the shrimp should be pierced through the top and again near the tail, so they're curled into a "C" shape.
Cook pineapple on the cool part of the grill until it is lightly caramelized. Remove, and assemble the skewers, alternating 2 pieces of shrimp and 3 of pineapple. Place over the coals, and grill ...