Char Siu Bao (Roti Babi Kukus)

Instructions

1. Heat oil in a pan and sauté the onion for 1 to 2 minutes. Add the char siu, soy sauce, oyster sauce, sugar, sesame oil, and red food coloring (if using). Stir-fry for 1-2 minutes, then add salt to taste.
2. Mix the cornstarch and water together, then add it to the filling. Simmer on low heat until the sauce thickens. Remove the filling from the pan and let it cool. Divide the filling into 16 portions and set aside.
3. Sift the flour, wheat starch, and powdered sugar into a large mixing bowl. Make a well in the center of the flour mixture and add the yeast, lukewarm water, and vinegar or lemon juice (if using). Gently dissolve the yeast in the water. Slowly incorporate the flour mixture and then add the vegetable oil.
4. Knead the dough by hand for 15 minutes, or until a soft, smooth, and shiny dough forms. Cover the dough with a damp cloth and let it rise for 60 to 90 minutes, or until it has expanded in size. Dissolve the baking powder in the cold water, then sprinkle it over the dough and knead until well combined. For fluffier buns, let the dough rest for 10 minutes after adding the baking powder.
5. Cut the dough into 16 equal portions and divide them accordingly.
6. Using a rolling pin, roll each dough ball into a 3-inch (7 cm) circle. Place a portion of the filling in the center.
7. Wrap and fold the dough over the filling.
8. Pinch and twist the dough to enclose the opening, ensuring the char siu bao is tightly sealed at the top. Place each bun on a 2" x 3" (5 cm x 7 cm) piece of parchment paper. Repeat until you have made 16 buns.
9. Arrange the buns in a steamer, leaving about a 1-inch (2.5 cm) gap between them. Spray a light mist of water over the buns and steam in a preheated steamer on high heat for 10 minutes. (You may add 1 teaspoon of Chinese white vinegar to help keep the char siu bao white.) Remove the buns from the steamer and serve warm.