Cut the tofu into bite-sized pieces.

In a bowl or bag, combine tofu with 1/2 cup of orange juice concentrate, cornstarch, ginger, and chili sauce.

Refrigerate and let marinate for about 1 hour.

Cook spaghetti to al dente.

Drain the spaghetti and set aside.

Drain tofu, reserving the marinade.

In a large skillet, combine marinade, stock, and remaining orange juice concentrate.

Cook over medium-high heat until the sauce reduces and thickens.

In a large skillet, heat 1 teaspoon of sesame oil and add tofu.

Sauté until browned and heated through.

Meanwhile, in a large wok, add 1 teaspoon of sesame oil over medium-high heat.

Sauté red pepper, snow peas, onion, green onion, mushrooms, bok choy stems, and carrots until tender but still crisp.

Add bok choy leaves, tofu, spaghetti, and sauce to the wok.

Stir to combine and serve immediately.