Start by cutting the extra-firm tofu into bite-sized cubes. In a mixing bowl, evenly toss the tofu with cornstarch, salt, and garlic powder until each piece is fully coated. Set aside.

In a large wok or non-stick pan, heat vegetable oil over medium-high heat until shimmering, about 2-3 minutes. Carefully add the tofu cubes in a single layer, frying for approximately 10-15 minutes until golden and crispy. Transfer to a paper-lined plate.

Lower the heat to medium and add whole peppercorns to toast them for 1-2 minutes, stirring gently to release flavor.

Introduce sliced celery, diced onion, minced garlic, and fresh ginger to the pan. Stir-fry vegetables for about 3-5 minutes, allowing celery to soften slightly while retaining crunch.

Return the crispy tofu to the pan and pour in low-sodium soy sauce and freshly cracked black pepper. Stir well and simmer for 3-5 minutes.

Once the sauce thickens and coats the tofu, serve immediately over cooked rice, enjoying the contrast of crispy tofu with vibrant vegetables.