In a small saucepan, whisk together the water and flour for the tangzhong. Cook over medium heat, whisking constantly for 4–5 minutes until thick and paste-like. Transfer to a bowl and set aside.
In a small bowl, combine milk, heavy cream, and vinegar. Set aside.
In a stand mixer bowl, mix bread flour, sugar, cocoa powder, yeast, and salt.
Add the milk mixture, egg, tangzhong, and red food coloring. Knead on low speed for 2 minutes until shaggy.
Add softened butter gradually, mixing well between additions.
Continue kneading for 10–12 minutes until smooth and elastic.
Shape into a ball, cover, and let rest for 30 minutes.
Mix filling ingredients until smooth.
Roll dough into a 15×21-inch rectangle. Spread filling evenly.
Cut into 12 strips and roll each strip tightly. Arrange in a parchment-lined 9×13 pan.
Cover and let rise 1–2 hours until doubled. Preheat oven to 325°F (162°C).
Bake 28–35 minutes until internal temperature reaches 185°F.
Beat butter and cream cheese until smooth. Add powdered sugar, then vanilla and cream. Whip until fluffy.
Cool rolls 15 minutes, frost generously, and allow frosting to melt into the warm red velvet cinnamon rolls before serving.