To press the tofu, drain the tofu and wrap it in a cloth or paper towel. Set the tofu on a plate and place another plate on top of the tofu. Place a heavy object on the top plate and refrigerate for at least 5 hours, preferably overnight.
Drain the pressed tofu and slice into 1/2 inch slices.
Combine 2 tbsp soy sauce and 1 tbsp apple cider vinegar in a shallow dish. Marinate the tofu in this mixture.
Heat about 1/4 inch of oil over medium heat. You want about half of the tofu slice to be submerged in the oil.
Coat each slice of tofu with cornstarch. I find the easiest way to do this is to sift the cornstarch onto the tofu. Flip and repeat for the back side.
Cook the tofu slices in the oil until golden brown. Flip and repeat. Remove and drain on a paper towel or wire rack.
Sauce
Heat 1 tbsp of oil in a skillet over medium low heat.
Combine soy sauce, apple cider vinegar, water, white sugar, brown sugar and cornstarch.
Saute the garlic and red paper flakes for 30 seconds - 1 minute. Make sure not to burn the garlic!
Add the liquid mixture to the pan. Cook until just boiling and until thickened.