Cut beef into 1/2-inch cubes. Toss with thyme. Season with salt and pepper. Heat 2 tablespoons oil in skillet. Stir in green pepper, green onion, celery and mushrooms. Cook until tender; remove from pan. Add remaining tablespoon oil to pan. Stir in beef. Cook until browned. Stir in water, wine, beef bouillon cubes and Worcestershire sauce. Simmer, covered, 30 minutes. Stir in rice, cook 25 minutes longer, or until rice is tender. Stir in precooked vegetables, stirring constantly until heated through.