Soak tofu skin a large bowl of water for about 30 minutes or until softened. Remove from water. Roll the skins into a cylinder and cut them crosswise into 1/4" slices.
Bring a pot of water to a boil. Add the tofu strands and simmer for about 10~15 minutes or until tender. Drain and set aside.
Heat 2tbsp oil in a wok or pan over high heat. Add bok choy and stir fry until tender crisp, about 1~2 minutes. Add the green onion and garlic and stir fry until light brown and fragrant, about 1 minute.
Add dry red chilies, tofu skin and soy sauce. Stir fry until tofu skins absorb the seasonings. Season to taste with salt.
Remove from heat and sizzle in the sesame oil. Serve immediately.