Prepare the Workspace: Dust a large baking sheet with baked cornstarch. Set up a silicone donut mold or small round containers for shaping.
Cook the Sugar Syrup: In a saucepan, combine sugar, corn syrup, water, and vinegar. Stir over medium heat until sugar dissolves. Attach a candy thermometer and cook without stirring to 260–265°F (hard ball stage), about 20–30 minutes. Add food coloring if desired.
Cool the Syrup: Cool syrup to 212°F, then pour into molds to form a donut-shaped puck. Let cool for 1–2 hours until pliable.
Stretch the Candy: Dust hands and puck with cornstarch. Press a hole in the center to form a ring. Stretch and rotate gently, keeping thickness even. When 12 inches in diameter, twist into a figure-8, fold into a ring, and stretch again. Repeat 10–12 times to create thousands of strands.
Add the Filling: Tear off 4–8-inch strand sections. Place 1 tsp of peanut-sesame-coconut filling in the center, fold, and roll gently to encase.
Serve: Use chopsticks to wrap strands into bundles. Serve immediately for best texture.