Prep pumpkin puree: Peel, seed, and chop the old pumpkin into even chunks. Steam for 15-20 mins until a chopstick pierces through easily. Let it cool slightly, then blend in a blender with a splash of water until smooth. Measure 280g and let it reach room temp (hot puree kills yeast!).
Knead the dough: Stir 5g yeast into the cooled pumpkin puree until dissolved. Add 500g all-purpose flour, mix into flocculent crumbs with chopsticks, then knead by hand. Adjust moisture—add a bit more water if too dry, or extra flour if too wet—until you get a smooth, non-sticky dough (5-8 mins).
Shape and portion: No extra rise needed! Roll the dough into a uniform log, then cut into 100g portions. Knead each portion gently until round, smooth, and wrinkle-free to get that “glossy skin” look.
Proof the buns: Arrange the buns on a steamer rack (leave space for expansion). On cold days, place the steamer over warm water; on hot days, proof at room temp. Let rise until puffy—press lightly and it springs back instantly (30-40 mins, depending on room temp).
Steam to perfection: Bring water in the steamer to a rolling boil. Steam on high heat for 20 mins. Turn off the heat, let sit covered for 5 mins (no peeking!) to prevent shrinkage—this locks in the glossy texture.