Optional: Press tofu for 20-30 minutes. Pressing the tofu will help it get a little crispier and absorb more flavour but it's not necessary to the success of the recipe. Use a tofu press or wrap in a dish towel and place a heavy object on top of it.
If you plan to serve this recipe with rice as recommended, start cooking that now, according to package instructions.
Cut the tofu into approximately 1/2-inch cubes and toss with the cornstarch and soy sauce. Set aside and heat 1 tsp of oil in a large skillet over medium heat.
Add the tofu and cook for about 60-seconds on each of the 6 sides until each piece is browned and crispy. Remove from the pan.
Gently wipe the pan to remove any residue from the tofu. Add the oil, then add the ginger, garlic, and onion. Saute for 4-5 minutes until softened, fragrant and translucent.
While the onions, ginger, and garlic are cooking, mix the sauce ingredients together in a bowl. Make sure the sugar and cornstarch are fully incorporated before you add the sauce to the pan.
Add the sauce and scallions to the pan and cook for 3-4 minutes, stirring and scraping the pan often, until the sauce is thick and sticky.
Add the tofu to the pan and mix to coat with the sauce. Cook for 1-2 minutes until the tofu is hot and coated in sauce.
Serve or your favorite rice and topped with thinly sliced scallions and fresh chopped cilantro.