Once your tofu has been pressed, cut it into roughly 1" cubes, or tear it into bite-sized pieces. (I prefer to tear mine, because the irregular pieces develop a nice crispy, craggy texture that holds sauce even better.)
Place the tofu pieces in a mixing bowl. Drizzle on the olive oil, then sprinkle over the onion powder, garlic powder, salt, and pepper. Give the pieces a toss to coat — try to be gentle so the tofu pieces don't crumble. A flexible rubber spatula can be really helpful here. (Or, if you have a container with a lid, you can simply give everything a gentle shake to coat.)
With the tofu pieces coated in oil and seasonings, now add the cornstarch and give the tofu another gentle toss to coat.