Preheat the oven to 425. Place cubed tofu in a large bowl. Add cornstarch, salt and pepper, and lightly drizzle with olive oil. Gently mix with your hands until the tofu is evenly coated. Place tofu on a parchment paper lined baking sheet and bake for 25 minutes or until outsides are golden brown and crispy.
While tofu is cooking, mix together all sauce ingredient except cornstarch. Place sauce mixture into a small pot and heat on high until the sauce begins to boil. Once boiling, add cornstarch, reduce heat to low, and stir until fully combined. Allow sauce to thicken a bit (about 2 mins).
When tofu is done, remove it from the oven and pour the sauce on top or serve it on the side to dip the tofu cubes.
Notes
Press tofu by laying a paper towel on a plate and putting the tofu cubes on top. Place another layer of paper towels on top of the tofu cubes and place another plate on top to add extra weight. Allow tofu to press overnight in the refrigerator.