Preheat oven to 425°F
Using your hands, tear the pressed tofu into bite-sized pieces. Place the tofu in a large bowl with the broth, gently tossing until the cubes are coated. Sprinkle in the cornstarch, salt, gochugaru flakes (if using), and pepper. Continue to toss until the tofu pieces are coated in the seasoned cornstarch.
Transfer the tofu bites onto a parchment paper lined baking tray and spray with a bit of oil. Bake on the middle rack of the oven until they're a light golden-brown and start to crisp around the edges, 20 to 30 minutes, flipping and spraying the other side with oil halfway through. Reduce the oven temperature to 350°F.
While your tofu bites are in the oven, get started on the Korean BBQ sauce.
In a large sauté pan over medium heat, add tamari, gochujang, coconut sugar, garlic, ginger, rice wine vinegar, cornstarch mixture, chili garlic sauce, toasted sesame oil, and black pepper. Whisk to combine and bring the sauce to a simmer. Reduce heat to low and simmer until it thickens and reduces in size about a third, about 5 to 7 minutes, whisking often.
Toss the baked tofu pieces with the sauce, ensuring each piece is thoroughly coated. Place the tofu bites back into the oven until caramelized and crispy, 10 to 15 minutes.
Once the tofu bites are done baking, remove from the oven and sprinkle them with toasted sesame seeds and chopped fresh green onion. Let cool about 5 minutes before serving.