Preheat the oven to 450°F 

In a food processor, combine the flour, baking powder, and cold butter. Pulse until the butter pieces are about the size of peas.

In a small bowl, mix the milk and vinegar. Pour the milk mixture into the food processor and pulse just until the dough comes together.

Lightly flour a clean counter and transfer the dough onto it. Dust the top of the dough with a little flour. Flatten the dough with your hands into a rectangle about ½ inch thick.

Cut the dough into squares approximately 1.5 inches each. Place the squares on a parchment-lined baking sheet.

Bake for 8–10 minutes, or until the biscuits are just lightly browned. (They will finish cooking when added to the soup.)

Add to your soup.