Drain the tofu. We have found that the longer you do this, the crunchier the tofu becomes. So we now leave it there all day or even overnight.
Place the tofu slice in a colander or in the basket of a steamer. Put a pan under the colander to catch the drained liquid.Cover the tofu with a plate. Put something very heavy on top of the plate. We use our mortar for this but a 3-litre bottle of water works fine too.
Then leave for at least 6 hours but better still longer.
Now slice the tofu into small dice.
Roll the tofu cubes through the cornstarch.
Heat the sunflower oil in a wok or frying pan until hot. Then add the tofu cubes and garlic and fry for a few minutes until golden brown. Shake the pan regularly so that all sides of the cubes have turned crisp. Drain on a paper towel.
Sauce
Mix all the sauce ingredients together. Heat the sauce while stirring to allow the cornstarch to bind the sauce.
Mix the fried and drained tofu cubes into the sauce. Garnish with the sesame seeds. Serve while hot.