Stir together the soy milk and vinegar in a small mixing bowl. Let rest for at least 10 minutes before using.
In a large mixing bowl, use a wooden spoon to mix together your dry ingredients: flour, baking powder, salt.
Using a knife, slice the vegan butter into smaller chunks (no need to be exact about the size of chunks). Cut the butter into the flour mixture using a pastry cutter, forks, or your fingers. The butter should be pea-sized.
Using a wooden spoon, stir the buttermilk into the dry mixture. Stir until the dough holds to the wooden spoon. You want the dough to be slightly sticky, but not so much so that it sticks to your hands.
Turn the biscuit dough onto a well-floured surface. Use your hands to flatten it to about half an inch thick. Fold the dough over on itself, then pat back down to half an inch thick. Repeat 2-3 times, making sure not to overwork the dough.
Use a biscuit cutter or knife to cut the biscuits into ~3 inch rounds. Place biscuits 2 inches apart on a parchment-paper-lined baking sheet.
Bake at 425 F for 15-18 minutes or until golden brown.
Biscuits will keep for 2-3 days at room temperature but will have the best quality if enjoyed the same day.
Keep your ingredients cold. Chill diced butter for at least 10 minutes before using for best results. You can even chill your mixing bowl and utensils before using. It's okay to skip this step if you're short on time.
To make pull-apart biscuits with soft sides, line cut biscuit dough up on the baking sheet so that the edges are almost touching.
For a consistent measure, spoon flour into the measuring cup instead of scooping the measuring cup into the flour. Use the back edge of a knife to sweep off excess flour.
Handle the dough as minimally as possible to keep a light texture. Overworking the dough can make the biscuits tough.