Preheat the oven to 450 degrees F and line a baking sheet with parchment paper.
In a small mixing bowl, combine milk and vinegar; whisk well and set aside for a few minutes to activate as this will serve as your “buttermilk” in the recipe; whisk in chilled sweet potato puree and maple syrup.
In a large bowl, whisk the flour with the baking soda and salt.
Sprinkle the shortening in tablespoon-size spoonfuls over the dry ingredients. Using a pastry cutter, two table knives, or a single fork, cut the shortening into the flour mixture until the mixture resembles very coarse crumbs, with some pieces of shortening the size of peas. Stir in the sweet potato mixture just until a soft dough forms.
Transfer dough onto a floured work surface and using your hands, pat into a 1-inch-thick round disc. Using a 2-inch round biscuit cutter, stamp out as many biscuits as you can. Using the scraps together, gently re-form a disc and stamp out more biscuits. Repeat until all dough has been used.
Arrange the biscuits on the prepared baking sheet and bake for 15 minutes or until golden brown.
Note: These make a delicious addition to a Thanksgiving spread with some vegan gravy or are perfect the next morning for brunch with almond butter and jam.