Cut tofu into cubes(about 2cm*2cm),add 5 tbsp corn starch and coat the tofu with corn starch. Cut garlic and scallion into small pieces.
Get a bowl, add sugar, salt, soy sauce, vinegar, ketchup, water and 1 tbsp corn starch, mix it well.
Heat up the wok(medium heat), when it’s hot enough add oil, add tofu, pan-fry until both sides are golden then take them out. The tofu might stick together because of the starch, separate them carefully with spatula or chopsticks while pan frying.
Add garlic to the wok, stir for 15s add tofu, then add the sauce from step 2.
Let it cook for about 5 mins until the sauce has thickened, sprinkle the scallion.