1. In a large wok or nonstick skillet, heat the 2 tablespoons oil over medium-high heat. Add the meat and stir-fry until no longer pink, about 1 minute. Remove the meat. Add the carrots, the broccoli and green beans, if using, the water chestnuts, mushrooms, onion, and ginger, and more oil if needed. Stir-fry until crisp-tender, about 3 minutes.
2. Return the meat to the wok and stir in the snow peas and soy sauce. Cover with spinach leaves, then cover the wok and heat through until the spinach is wilted, 1 to 2 minutes. Serve over brown rice.