Preheat oven to 375* F.
Into a medium bowl, combine sugar, oil, plant milk, vanilla and lemon juice or vinegar with a whisk. Place a sifter on top of the bowl with the wet ingredients in it and add flour, baking powder, baking soda and salt to the sifter and sift the dry ingredients into the wet ingredients. Combine with a whisk.
Add rainbow sprinkles into the batter and stir with a spatula to evenly distribute.
Line a baking tray with parchment and using a 1 ½ tablespoon cookie scoop, portion the batter onto trays leaving 2 inches of space in between for spreading.
Bake in a 375* oven for 10-12 minutes. The whoopie pies will lightly spring back when pressed in the center with a finger. Remove from the oven and let cool on the pan for 5 minutes before moving to a cooling rack. And then repeat the process with the remaining batter.
Fill with desired filling- Chantilly cream, buttercream, jam or ganache- and serve! I have linked my recipes for Chantilly and buttercream above!