01 - Cut firm tofu into 1-inch cubes. Dissolve 1 teaspoon salt in 2 cups water and submerge tofu cubes for 10 minutes to infuse flavor. Drain thoroughly and pat dry with paper towels to remove excess moisture.
02 - In a mixing bowl, combine rice flour, cornstarch, white pepper, garlic powder, turmeric powder if using, and 1/2 teaspoon salt. Gradually whisk in 1/2 cup cold water until a smooth, thin batter forms without lumps.
03 - Pour vegetable oil into a deep pan or wok until 2-3 inches deep. Heat to 340°F, maintaining steady temperature throughout frying.
04 - Dip each seasoned tofu cube into the batter, allowing excess to drip off. Carefully lower battered tofu into hot oil. Fry in batches, turning occasionally for even cooking, until golden brown and crispy, approximately 5-7 minutes per batch.
05 - Remove fried tofu using a slotted spoon and transfer to paper towels to drain excess oil. Serve immediately with fresh bird's eye chilies and sweet soy sauce on the side for dipping.