Rinse, dry, shell, and devein the shrimp if necessary, but leave the tails on. Split the shrimp along the inner curve, but do not cut all the way through. Spread each shrimp out flat and tap with the broad of a cleaver or knife. (Cutting along the inner curve prevents the shrimp from curling out of shape during the cooking.)
Make the marinade by combining in a bowl the ginger, garlic, and oil. Season shrimp with the marinade, cover and chill 30 minutes.
Make the batter by measuring out the dry ingredients into a mixing bowl and then adding the liquid ones, singly and little by little, stirring until the mixture is a smooth, thick batter. Fold in the sesame seeds last. Place the batter by the shrimp near the stove.
Heat the wok or heavy, deep pot; then add and heat the oil until a drop of batter foams instantly, about 375 degrees F. Lower the heat a little. Then hold 1 shrimp by its tail and dip it into the batter to coat evenly; slip it into the hot oil. Repeat rapidly with the rest of the shrimp and deep-fry them for 3 minutes. Turn the shrimp constantly, with a gentle motion, after they're all in the oil. When they are golden brown, remove them with chopsticks, a skimmer, or a slotted spoon to paper towels to drain.
Arrange the shrimp on a serving platter and sprinkle a little roasted salt-pepper on top. The shrimp may be done 10 to 15 minutes in advance and kept hot and crisp in a 200 degree F oven. Or decrease the frying time by 30 to 45 seconds; then drain on paper towels. When ready to serve, refry until brown and crisp, about 30 seconds.