Mix together lavender and milk in a medium sized sauce pan over medium low heat and let come to a simmer that's almost boiling.
Take off the heat, cover, and let sit for 15 minutes.
Strain into a medium bowl, getting as much of the milk as you can, and let cool completely in the fridge or freezer.
Preheat the oven to 350℉ and line a muffin tin with cupcake liners.
Add apple cider vinegar to cooled milk and let curdle for a few minutes.
Whisk in oil, sugar, and vanilla extract.
In a seperate large bowl, whisk together flour, cornstarch, baking powder, baking soda, and salt.
Add wet ingredients to dry and mix until JUST combined and most flour clumps are gone.
Pour into liners, filling ⅔ of the way, and bake for 20-22 minutes. Let cool completely before frosting.