Press the 400 g extra firm tofu for 30 minutes to remove the excess moisture. You can do this by placing the block of tofu on a rimmed plate or tray, then topping with something flat like a plate and placing a heavy object on top (cast iron skillet or pot of water). After pressing for 30 minutes, pour off the extra liquid.
The Sauce
While the tofu is pressing, make the honey sriracha sauce. In a small bowl, combine the 1 Tbsp. sriracha, 2 Tbsp. honey, 1 tsp. soy sauce, and the 1/4 tsp. crushed red pepper. Set the sauce aside.
The Tofu
Cut the pressed 400 g extra firm tofu into ½-inch cubes. Use a paper towel to lightly pat dry the tofu cubes.
In a mixing bowl, add the 2 Tbsp. vegetable oil and 1 tsp. soy sauce. Lightly whisk the soy sauce into the oil. Add the cubed tofu and gently stir until the tofu is coated in oil and soy sauce. Sprinkle 1 Tbsp. cornstarch over the cubed tofu and gently stir.
Heat a frying pan over medium. When the skillet is hot, add the prepared tofu. The tofu will fry in the oil that is coating the cubes. Cook the tofu, stirring only occasionally, until it is brown and crispy on all sides for about 10 minutes. Pour the honey sriracha sauce over the tofu and continue to stir and cook for 1-2 more minutes, or until the glaze is thick and sticky.
The Serving
Top the honey sriracha tofu with the sliced 2 green onions and roasted white sesame seeds and serve with rice or pasta.