Allow to sit for 10 minutes, until it starts to slightly curdle.
Notes
Try experimenting with salad dressings, whipping up some delicious pancakes, or soaking chicken breasts just before baking. This method can be used to make dairy-free or vegan buttermilk alternatives by using any milk. No lemon juice? You can use vinegar instead. Use clear vinegar, like plain distilled vinegar, apple cider vinegar, or rice vinegar.