Drain the 800g of extra-firm tofu, wrap it in paper towels or a clean kitchen towel, and set a light weight on top, such as a plate with a can resting on it. Press for 30 minutes, replacing the towel once if it becomes very wet. Unwrap the block and cut it into medium cubes, about 3cm / 1¼ in. The tofu should feel noticeably firmer and look dry on the surface, with no water beading when you press a cube gently. That thorough draining is what keeps the coating even later and stops the hot oil from spitting.

In a small bowl, stir together 1¼ tsp fine sea salt, 1 tsp freshly cracked black pepper, ½ tsp sugar, and ¼ tsp white pepper if using. Add the ¼ tsp five-spice powder or a pinch of ground Sichuan peppercorn only if you want extra fragrance, and keep it light so the black pepper still leads. Leave the blend dry and set the bowl beside the stove, with a rack or a paper-towel-lined plate ready for the fried tofu. Chop the garlic and slice the chilies and scallions now as well. That advance setup is what lets the final toss take seconds, while the crust is still crackling.

Pat the cubes dry once more with fresh paper towels, then tip them into a large bowl. Add 2 tbsp cornstarch, 2 tbsp rice flour or plain flour, and ½ tsp fine salt, and toss gently until every cube wears a light, even, almost translucent coating. Shake off the loose powder in a sieve or by hand; the surface should look dusty, not pasty or shaggy. Coat the tofu just before it goes into the oil, since the starch turns gummy if it sits against damp cubes. That thin shell is what fries into a genuinely delicate, crisp crust instead of a heavy batter.

Pour neutral oil into a wide, heavy pan to a depth of 1.5–2cm and heat to 175–180°C; a cube lowered in should sizzle at once and keep bubbling steadily. Fry the tofu in 2–3 batches, leaving space between the cubes, for 4–6 minutes per batch, turning every minute or so, until evenly golden and crisp on every side. Lift each batch onto a rack or paper towels to drain, and let the oil climb back to 175–180°C before the next batch goes in. That uncrowded, properly hot frying is what keeps the tofu genuinely crisp instead of oily.

For a crunchier crust that holds longer, let the fried tofu rest for 2 minutes, then return it to the oil over slightly higher heat for 45–60 seconds. The cubes should turn a deeper gold and sound crackly against each other when stirred. Drain them again on the rack or paper towels. Skip this step if you prefer a softer, more tender crust, since the first fry already gives a genuinely crisp result. That short second pass is what drives out the last surface moisture and firms the shell.

Pour off most of the frying oil and wipe out the pan if any burnt crumbs remain. Return it to medium heat with 1 tbsp fresh neutral oil, then add the 5 chopped garlic cloves and stir just until lightly golden and fragrant. Add the red and green chilies and stir for 15–20 seconds, then add 3 of the 4 sliced scallions and toss briefly. The garlic should be pale gold, never dark brown, so lift the pan off the heat at once if it colours too fast. That restraint is what keeps the garlic genuinely sweet and aromatic instead of bitter.

Return the fried tofu to the pan and raise the heat to medium-high. Sprinkle over the salt and pepper seasoning and toss quickly and briefly until every cube is evenly flecked with pepper. Scatter in the remaining 1 scallion, toss once more, and tip the tofu onto a warm platter straight away. Serve immediately, ideally with steamed rice, stir-fried greens, or a cucumber salad. That short, fairly hot toss is what seasons the tofu genuinely evenly without letting steam soften the crust.