Gather the ingredients.
Take the tofu out of the package and drain excess water. Place the tofu between two plates and top with something heavy (I used a cast iron pan). Set aside for 15 to 20 minutes while you prepare the other ingredients. Do this step near a sink so you don't spill water everywhere when you drain the tofu. Learn from my mistake.
Prepare the teriyaki sauce. In a small bowl, combine soy sauce, brown sugar, and mirin. In another bowl, combine the water and corn starch. Set aside.
Remove the plate from the tofu and drain any water that has pressed out. Cut the tofu into about one inch cubes.
In a plastic bag, combine 1/2 cup of corn starch with the cubes of tofu. Close the top and shake the bag so the tofu is coated. Take out pieces of tofu and tap off any excess starch.
In a pan, heat up frying oil over medium heat. Place the tofu into pan, making sure tofu pieces do not touch.
Fry for 3-5 minutes on each side or until golden brown. When the tofu pieces are fried, remove and turn heat to low.
In the pan, toss in green onions and garlic. Fry for 30-60 seconds, making sure not to burn the garlic.
Pour in the reserved teriyaki sauce. Let it simmer and reduce for 60 seconds. Add in the cornstarch mixture and simmer until desired thickness. If the sauce gets too thick, just add more water.
Turn off the heat and add the fried tofu. Toss to coat in sauce. Plate and enjoy!