Step 1: In a medium saucepan, melt the butter over medium heat. Once melted, add the milk, granulated sugar, and salt. Stir until the sugar and salt are fully dissolved. Bring the mixture to a gentle simmer, then remove from heat.
Step 2: Add the silken tofu to the warm milk mixture. Use an immersion blender or transfer to a regular blender and blend until completely smooth and creamy. Ensure there are no lumps of tofu remaining.
Step 3: In a large mixing bowl, combine the tapioca flour, all-purpose flour, and baking powder. Whisk them together thoroughly to ensure even distribution.
Step 4: Pour the warm tofu-milk mixture into the dry ingredients. Mix with a rubber spatula until a shaggy dough forms.
Step 5: Turn the dough out onto a lightly floured surface (using tapioca flour). Knead for about 5-7 minutes until the dough is smooth, elastic, and no longer sticky. It should feel soft and pliable.
Step 6: Divide the dough into 12 equal portions. Roll each portion into a small ball.
Step 7: To form the classic Pon De Ring shape, arrange 8 small dough balls into a circle on a 3×3 inch square of parchment paper, pressing them gently together to connect. Alternatively, you can roll each portion into a rope, then connect the ends to form a ring, and then lightly pinch off 8 equal segments along the ring to create the characteristic shape.
Step 8: In a deep, heavy-bottomed pot or Dutch oven, heat about 3-4 inches of vegetable oil to 340-350°F (170-175°C). Use a thermometer to monitor the temperature, as consistent oil temperature is key for perfect donuts.
Step 9: Carefully lower the parchment paper squares with the formed donuts into the hot oil, parchment side up. The parchment paper will peel off easily after a minute or two; remove it with tongs. Fry 2-3 donuts at a time, depending on the size of your pot, to avoid overcrowding and dropping the oil temperature.
Step 10: Fry for 2-3 minutes per side, or until golden brown and puffed up. Use a slotted spoon or spider to flip them gently. The donuts should be evenly colored.
Step 11: Remove the fried donuts from the oil and place them on a wire rack lined with paper towels to drain excess oil.
Step 12: While the donuts are cooling slightly, prepare your desired glaze. For a simple sugar glaze, whisk together powdered sugar and milk (or water/lemon juice) until smooth. Dip the warm donuts into the glaze, letting any excess drip off.
Step 13: Allow the glaze to set for a few minutes before serving. These donuts are best enjoyed fresh.
Step 14: Store any leftover donuts in an airtight container at room temperature for up to 2 days, though their texture is best on the day they are made.