Cut pork across grain in thin slices, then in strips. Coat with mixture of 2 teaspoons each cornstarch and soy sauce with half of the garlic; let stand 30 minutes.
Meanwhile, combine 3/4 cup water, 1 Tablespoon cornstarch, 4 teaspoons soy sauce and red pepper set aside.
Stir-fry pork in 1 Tablespoon hot oil in work or large skillet over high heat 2 minutes; remove. Stir-fry cauliflowerets and remaining garlic in 2 Tablespoons hot oil in same pan over medium-high heat 2 minutes. Add green pepper; stir-fry 3 minutes. Add tomatoes, pork and soy sauce mixture. Cook and stir gently until sauce boils.