Partially freeze meat about 30 minutes. Thinly slice across the grain into bite-size strips. For sauce, stir together 1/4 cup water, the tomato juice, cornstarch, chili powder, lemon juice, sugar, and ground red pepper.
Spray an unheated wok or 12-inch skillet with nonstick coating. Preheat over medium-high heat. Add fresh green beans (if using). Stir-fry for 3 minutes. Add celery. Stir-fry for 2 minutes. Add sweet pepper and thawed frozen beans (if using). Stir-fry about 1-1/2 minutes more or until vegetables are crisp-tender. Remove from wok.
If necessary, add oil to hot wok. Add pork. Stir-fry for 2 to 3 minutes or until cooked through. Push pork from center of wok.
Stir sauce; add to center of wok. Cook and stir until thickened and bubbly. Return vegetables to wok; stir to coat. Cook and stir for 2 minutes more. Serve with hot cooked rice.