Start by dicing your char siu pork and finely chopping the onion. In a skillet over medium heat, cook the onions until they're translucent, about 3–4 minutes. Then, mix in the char siu, dark brown sugar, oyster sauce, hoisin sauce, chicken broth, and sesame oil. Allow the filling to simmer for about 10 minutes until flavors meld, then stir in a cornstarch slurry to achieve a thick, luscious texture.

While the filling simmers, take your frozen dinner roll dough and lay it out on a baking sheet. Cover it with a clean kitchen towel and let it thaw for approximately 3–4 hours at room temperature until the dough has doubled in size and feels soft to the touch.

Once the dough has risen, preheat your oven to 375°F (190°C). Lightly flour your work surface and gently flatten each dough ball into a circle, approximately 4–5 inches wide. Spoon a generous amount of the char siu filling into the center of each circle, then carefully pinch the edges together to seal.

After assembling the manapua, cover the buns with a towel and allow them to proof for about 30 minutes.

Once the buns have proofed, brush the tops with an egg wash for a golden shine. Carefully place the baking sheet in your preheated oven and bake the manapua for about 20 minutes or until they are golden brown and puffed up.