In a medium size bowl combine flour, 2 tbsp cornstarch, baking soda, baking powder and whisk. Pour in 2 tbsp soy sauce, dry sherry, 2 tbsp water, vegetable oil, and a dash of sesame oil; stir until smooth. Stir in chicken until coated with batter, cover, then refrigerate for 20 minutes.
Meanwhile in a large skillet or wok, bring chicken broth, sugar, rice vinegar, soy sauce, sesame oil, Siracha hot sauce, and garlic to a boil over high heat. Dissolve 1/4 cup cornstarch into 1/2 cup water, and stir into boiling sauce. Simmer until the sauce thickens, about two minutes. Reduce heat to low, and keep warm.
Heat oil in a deep fryer or large saucepan to a temp. of 375 degrees. Drop in the battered chicken pieces, only a few at a time and fry until they turn golden brown; about 3-4 minutes per batch. Drain on a paper towel lined plate.
You can either toss chicken in the sauce or serve with the sauce over top. Sprinkle with sesame seeds to garnish. Enjoy!!