Step 1: In a large mixing bowl, whisk together the mochiko flour, granulated sugar, baking powder, and salt until well combined and lump-free.
Step 2: In a separate medium bowl, mash the silken tofu until completely smooth. Add the milk, 2 tablespoons vegetable oil, and vanilla extract, whisking until fully incorporated.
Step 3: Pour the wet ingredients into the dry ingredients. Mix with a rubber spatula until just combined into a thick, sticky dough. Do not overmix.
Step 4: Transfer the dough to a piping bag fitted with a large star tip (or a sturdy Ziploc bag with a 1/2-inch corner snipped off).
Step 5: Cut parchment paper into 3x3 inch squares and lightly grease them. Pipe 8 small, connected balls in a circle onto each parchment square to form the classic 'pon de ring' shape. Ensure there's a small hole in the center.
Step 6: Heat 2-3 inches of vegetable oil in a deep pot or Dutch oven to 325-350°F (160-175°C). Use a candy thermometer to maintain the temperature.
Step 7: Carefully lower one parchment square with the dough into the hot oil. The parchment paper will release easily after about 30 seconds; remove it with tongs.
Step 8: Fry 2-3 donuts at a time for 3-4 minutes per side, or until golden brown and puffed. Flip gently with a slotted spoon or spider strainer.
Step 9: Remove fried donuts and place them on a wire rack set over a baking sheet to drain excess oil. Allow to cool slightly.
Step 10: To make a simple glaze, whisk powdered sugar with milk and vanilla extract until smooth. Dip each cooled donut into the glaze, letting excess drip off, then place back on the wire rack to set. Serve immediately or store in an airtight container.