I would be too embarrassed to serve this easy appetiser to an Indian person, who, I'm sure, would think of it as an abomination of their cuisine. The recipe uses curry powder, which doesn't actually exist in India, where spice blends are made fresh according to whatever main ingredients they're cooked with.
Still, though, for something this easy, the results are good. But please make sure the curry powder you pick is well-balanced, and doesn't consist almost solely of turmeric with a little chilli powder mixed in.
Kaffir lime leaves come in pairs; you need two medium-sized pairs for this recipe.
Make the salsa. Cut each mango by slicing parallel to the large, flat pit in the centre, then turn over and cut the other side, again, parallel to the pit. When you finish, you will have three pieces: the pit, plus two "cheeks". Carefully cut the flesh of the mango cheeks in a 1cm (7/16in) crosshatch pattern, down to the skin. Use a large spoon to scoop the flesh from the skin and put the mango pieces into a bowl.
Mince the shallots and chillies. Separate the kaffir lime leaves into individual leaves, then cut out the thick vein that runs down the centre of each one. Stack the pieces then cut them into very fine pieces. Mix together the mango, shallot, chillies and kaffir lime leaf, then add the coconut, lime juice and a little salt.
Mix the curry powder with the rice flour and sugar in a small bowl.
Remove the heads and shells from the shrimp. The heads and shells should be reserved for another dish.
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.
Lightly but evenly dust the seafood with the curry mixture and shake off the excess.
Heat a large skillet over a high flame. Lightly coat the skillet with oil. When the skillet is very hot, add the skewers and sear the seafood for about 45 seconds on each side, or until barely cooked through.
Place skewers onto plates, then add a large spoonful of the mango salsa. Serve immediately.