In a mixing bowl, combine the soy sauce, maple syrup, sesame oil, rice vinegar, garlic, ginger, gochujang, and black pepper to create the marinade.
Add the sliced tofu to the marinade, ensuring all pieces are well-coated. Let it marinate for at least 15 minutes.
Set your Instant Pot to the sauté mode and add vegetable oil. Once hot, add the marinated tofu. Sauté for 5-7 minutes or until slightly crispy. Remove from the pot and set aside.
In the same pot, add the sliced mushrooms and bell pepper. Sauté for about 3-4 minutes until softened.
Return the tofu to the pot and sprinkle cornstarch over the mixture. Stir well to combine.
Add a splash of water if necessary, then close the lid and set the Instant Pot to manual mode (high pressure) for 5 minutes.
Once cooking is complete, do a quick release of pressure. Carefully open the lid and stir the bulgogi.
Serve hot over cooked rice if desired, and garnish with chopped green onions and sesame seeds.