Cut chicken into 1-inch pieces. In a medium bowl combine egg, biscuit mix and water. Dip chicken pieces into batter to coat.
Heat 1-1/2 cups cooking oil in wok or small deep-fat fryer over medium heat (375 degrees F). Fry chicken pieces in hot oil, a few at a time, until golden brown (about 2 minutes). Remove chicken pieces as they brown and drain on paper towels. Discard cooking oil. Keep chicken warm in a 300 degree F oven.
For sauce, drain pineapple, reserving juice. Add enough water to juice to make 1-3/4 cups. In a bowl combine sugar, soy sauce, vinegar, cornstarch, and paprika. Add pineapple juice mixture; set aside.
Add 1 tablespoon cooking oil to the wok or 12-inch skillet. Preheat over medium-high heat. Stir-fry green sweet pepper and green onions in hot oil for 2 to 3 minutes or until crisp-tender. Remove vegetables from wok. Stir sauce; add to center of wok. Cook and stir until slightly thickened and bubbly. Add cooked vegetables, pineapple chunks, and tomatoes to wok. Cook and stir about 2 minutes more or until heated through. Add chicken; stir to coat. Serve immediately over cooked rice. Makes 6 servings.