Cube the tofu into approx 1.5 inch pieces. Coat the pieces evenly in corn flour. You want them coated well on all sides.
Mix all the sauces in a bowl and set aside. Add 2 tablespoons of water to this and stir. Set aside.
Heat half the oil in a wide pan over medium heat. Add the tofu pieces to the pan without overlaps.
Cook until they've crisped and browned on all sides, adding more oil if necessary. Remove and set aside.
Add the sauce to the same pan over medium heat. Cook for 2 mins (it will look watery at this stage, but the corn flour in the tofu will thicken it up).
Add the tofu to the sauce and cook over high heat until the sauce coats the tofu in a sticky glaze.
Toss in the sesame seeds and spring onion tops. Taste and adjust seasoning. Serve hot.