Prepare Tofu: Start by draining the firm tofu and pressing it gently to remove excess moisture. Use a tofu press or place a heavy object on top for about 15 minutes. Cut the tofu into bite-sized cubes or tear it into pieces for a rustic look.

Season Tofu: In a mixing bowl, toss the cubed tofu with olive oil, salt, pepper, and cornstarch until evenly coated.

Cook Tofu (Oven): Preheat your oven to 425°F (220°C). Spread the seasoned tofu in a single layer on a baking sheet lined with parchment paper. Bake for 15 minutes, then toss and bake for another 15-20 minutes until golden brown and crispy.

Cook Tofu (Air Fryer): Preheat your air fryer to 400°F (200°C). Add the seasoned tofu to the basket, ensuring not to overcrowd it. Air fry for 18-20 minutes, shaking the basket every 5 minutes.

Make Gochujang Sauce: In a saucepan, combine gochujang, ketchup, mirin, soy sauce, brown sugar, garlic, rice vinegar, and toasted sesame oil. Heat until bubbling, then reduce and simmer for 3-5 minutes.

Combine: Toss the crispy tofu in the gochujang sauce until well-coated. Serve warm over rice or alongside steamed vegetables, garnished with scallions and sesame seeds.