Remove the shrimp legs, leaving shells and tails on. Rinse the shrimp under cold water and set on several sheets of paper towels. With more paper towels, pat the shrimp dry. In a small bowl combine the salt, sugar, and chili powder.
Heat a 14-inch flat-bottomed wok over high heat until a bead of water vaporizes within 1 to 2 seconds of contact. Swirl in 1 tablespoon oil, and add garlic, sliced chilies and stir-fry 30 seconds. Add shrimp, 1 tablespoon oil and stir-fry 1 minute or until shrimp just begin to turn pink. Swirl in remaining 1 tablespoon oil, and add salt mixture, and stir-fry 1 to 2 minutes until shrimp is just cooked. Stir in scallions. Serves 4 as part of a multi-course meal.
