If desired, partially freeze meat for easier slicing. Thinly slice meat across the grain into bite-size strips. For sauce, stir together orange juice, hoisin sauce, ginger, and, if using, crushed red pepper. Set aside.
Remove strings and tips from fresh pea pods, if using; set pea pods aside. Pour oil into a wok or large skillet. (Add more oil as necessary during cooking.) Preheat over medium-high heat. Stir in carrots. Cook and stir for 2 minutes. Add pea pods and green onions. Cook and stir for 2 to 3 minutes or until vegetables are crisp-tender. Remove vegetables from wok.
Add half of the pork to hot wok. Cook and stir for 2 to 3 minutes or until no pink remains; remove from pan. Add remaining pork; cook and stir for 2 to 3 minutes or until no pink remains. Return all meat and vegetables to wok. Stir sauce; add to center of wok. Cook and stir until heated through. Stir in rice until coated. Top with nuts.