Preheat the oven to 350 degrees F. Line or grease the cupcake tray.
In a small bowl, whisk together the lemon juice and plant-based milk and allow it to sit for at least 10 minutes. The acid in the lemon juice is going to curdle the plant-based milk and create a homemade vegan buttermilk.
While you wait, combine the baking soda, salt, flour and cornstrach in a medium mixing bowl.
Add vegan butter to a bowl and mix until creamy, using either a hand mixer or stand mixer, scraping the side often.
Once the butter is beaten, add in the brown sugar and granulated sugar. Cream together until combined. Please note, it will still be a little gritty and you will need to scrape the sides and mixer.
Add in the vanilla extract and plant based milk + lemon mixture and mix again until combined.
Next, add in the prosecco and mix again. It will be very wet, but this is OK.
Slowly combined the flour mixture into the liquid mixture and mix until combined. This will take approx 2 minutes. A soft, fluffy batter will form, that is semi thick (it should not be drippy).
Using a spatula, gently fold the strawberries into the batter. Do not use an electric mixer, as it will cause the strawberries to burst.
Gently spoon approx 3 tbsp of the batter into each cupcake liner. It should be filled to the top.
Bake for 25-30 minutes, or until you are able to insert a toothpick and it comes out clean.
Cool for 15 minutes before frosting. Pro tip- While the cupcakes are cooling off, begin to make the frosting.