Cut the tofu into 2-centimetre (3/4-inch) cubes and dry well on paper towels. Put half the cornstarch into a food bag, add the tofu cubes and toss to coat, then add the remaining cornstarch and toss again. Set aside for 5 minutes to become slightly tacky.
Mix the rice vinegar, soy sauce, hoisin sauce and brown sugar together in a bowl and set aside.
Heat the sunflower oil in a wok or frying pan over a high heat and cook the tofu for 1 to 2 minutes on each side until golden brown. Remove from the pan and set aside to drain on paper towels. Drain any excess oil from the wok.
Allow the wok to cool a little, then add the sesame oil, ginger, garlic and chile and gently fry for about 1 minute before adding the blended sauce ingredients with 150 milliliters (2/3 cup) water. Bubble until you have a thick, glossy sauce.
Return the tofu to the pan and toss to coat all over. Serve with steamed basmati or brown rice and broccoli.