01 - Cut the tofu into 1-inch cubes. Dissolve 1 tsp salt in 2 cups water and soak tofu cubes for 10 minutes to season thoroughly. Drain well and pat completely dry with paper towels.
02 - In a mixing bowl, combine rice flour, cornstarch, white pepper, garlic powder, turmeric powder if using, and 1/2 tsp salt. Gradually whisk in 1/2 cup cold water until a smooth, thin batter forms without lumps.
03 - Pour enough vegetable oil into a deep pan or wok to reach 2-3 inches depth. Heat to 340°F, maintaining steady temperature throughout frying.
04 - Dip each tofu cube into batter, allowing excess to drip off, then carefully lower into hot oil. Fry in batches without overcrowding, turning occasionally, until golden brown and crispy, about 5-7 minutes per batch.
05 - Remove tofu with slotted spoon and drain on paper towels. Serve immediately with fresh chilies and sweet soy sauce if desired.