Cut pork into 4x1/4-in. strips; place in a large resealable plastic bag. Add garlic and 2 tablespoons soy sauce; seal bag and turn to coat. Refrigerate for 2-4 hours.
In a small bowl, combine the cornstarch, ginger, broth and remaining soy sauce until smooth; set aside.
Heat oil in a large skillet or wok over high heat; stir-fry pork until no longer pink. Remove and keep warm. Stir-fry carrots and celery for 3-4 minutes. Add the onion, cabbage and spinach; stir-fry 2-3 minutes longer.
Stir cornstarch mixture; stir into vegetables. Return pork to the pan. Bring to a boil; cook and stir for 3-4 minutes or until thickened. Serve with rice if desired.
I've been making this recipe since I first saw it in the magazine, quite a few years ago. I tastes great and is very forgiving regarding ingredients. You can use any type of meat or double up on the veggies if you want to go meatless. Tofu works well and added cashews are fun. I recommend this recipe.