Preheat the oven to 400°F. Line a baking sheet with parchment paper.
Toss the pressed and cubed tofu in 2 tablespoons of cornstarch until evenly coated. Spread in a single layer on the prepared baking sheet.
Bake for 20 minutes, then flip each cube and bake for an additional 15 to 20 minutes until light golden brown and crispy.
While the tofu bakes, set a large skillet over medium-high heat. Add the sesame seeds and toast for 1 to 2 minutes, stirring frequently, until just beginning to turn lightly golden. Remove from the skillet and set aside. Keep the skillet out.
When the tofu is done, return the skillet to medium heat. Add the sesame oil and garlic and cook for about 30 seconds until fragrant. Add the soy sauce and black pepper and stir to combine.
Add the baked tofu to the skillet and toss until every piece is fully coated in the garlic soy sauce.
Transfer to a serving plate, top with toasted sesame seeds and chopped green onion, and serve immediately.