Place two paper towels on a plate then place the entire block of tofu (drained from its packaging liquid) onto the plate. Place two more paper towels on top of the tofu then put a heavy item on top. Not too heavy that it would completely crush the tofu but heavy enough that it can squeeze out liquid. A cast iron skillet usually works well.
Leave for 30 minutes and halfway through, change out the paper towels.
Once the tofu has drained, slice in half then into cubes and place into a large bowl. Sprinkle cornstarch on top and gently toss with your hands to ensure all tofu pieces are covered.
In a large skillet, add sesame oil and vegetable oil then bring up to medium-high heat.
Once oil is heated, add the tofu to the skillet and let brown on all sides.
In the meantime, whisk together the ingredients for the sauce.
Once the tofu has browned and crisped up on all sides, add the sauce to the skillet and it should start to thicken immediately. Toss the tofu around to coat then remove from heat.