Cut the pressed tofu into bite-sized cubes, about 1-inch thick. Pat the cubes dry with paper towels to remove excess moisture.

In a large bowl, combine cornstarch, salt, black pepper, garlic powder, onion powder, and cayenne pepper (if using). Mix well.

Toss the tofu cubes in the cornstarch mixture until evenly coated. Shake off any excess cornstarch.

Heat about 1/2 inch of vegetable oil in a large skillet over medium-high heat. Once the oil is hot (about 350°F), carefully add the tofu cubes in a single layer. Fry in batches if necessary to avoid overcrowding.

Fry the tofu for about 3-4 minutes on each side, or until golden brown and crispy. Use a slotted spoon to transfer the tofu to a paper towel-lined plate to drain excess oil.

Once all the tofu is fried, sprinkle with additional salt and pepper to taste. Garnish with chopped green onions and serve with lemon wedges on the side.