Step 1Peel, devein and butterfly the shrimp.
Step 2In a bowl, mix the shrimp with one-quarter cup -cornstarch to completely coat the shrimp.
Step 3Combine the remaining 2 teaspoons cornstarch with 2 teaspoons water in a bowl and set aside.
Step 4Pour the oil into a skillet or wok and heat over medium heat until hot. Add the shrimp and deep-fry until golden, about 45 seconds.
Step 5Remove the shrimp and drain the oil from the wok, leaving 1 tablespoon for stir-frying. Reheat the wok. Add the garlic, ginger and cayenne. Stir for a few seconds, then add the tomato sauce, vinegar, wine, sugar, salt, one-quarter cup water and the reserved cornstarch mixture. Cook and stir until the sauce is thick.
Step 6Add the shrimp; toss until covered with sauce. Add the green onions, stir, turn out onto a platter and serve.