Combine in a bowl: Heat wok for 30 - 40 seconds. Add peanut oil & heat until white smoke rises. Add onion and cook over low heat until onions turn light brown. Add char siu, increase heat, stir fry until mixture well combined. Add wine and mix well. Reduce heat and add sauce mix from bowl. Stir until thickend. Add 1/2 tsp. sesame oil and mix well. Remove mixture to shallow dish. Allow to cool to room temp then refrigerate uncovered for 4 hrs.
Roll 1 recipe Steamed Bun Dough into a 16 inch long roll and cut into 16 1" pieces. Roll each into a ball and cover with damp cloth. Work dough ball into a hemisphere. Put 2 Tbs. filling mix into formed hemisphere in palm of one hand. Work around the hemisphere, pleating and closing the dough until filling is completely covered. Place sealed buns, sealed end down, on 2.5" X 2.5" squares of wax paper. Place in steamer at least 2" apart, steam for 15 - 20 minutes. Serve immediately.