Preheat the oven to 350 degrees F and line a 12-cup muffin pan (2 if you have them, if not bake one tray at a time) with paper liners. I usually spray the liners with a little oil as well to prevent sticking.
Combine the soy milk and apple cider vinegar in a measuring cup or bowl, give a little stir and set aside for a few minutes to curdle.
In a large bowl, whisk together the flour, sugar, baking powder and salt until combined.
Now pour in the milk/vinegar mixture, melted vegan butter or oil and vanilla. Whisk until well combined. There may be a few small lumps, but you don't want any large lumps in the batter.
Fill the liners 1/2 full and bake for 18-20 minutes, or until a toothpick comes out clean. Carefully transfer the cupcakes to a cooling rack, then place new liners in the pan and bake the rest of the cupcakes until you have used all the batter.
Cool completely, then pipe on Vegan Buttercream Frosting or another frosting of your choosing. Decorate with sprinkles or sliced strawberries. Enjoy! Store cupcakes on the counter, covered for up to 4 days (they stay moist!). They also freeze perfectly for up to 3 months, with or without frosting.