If a recipe calls for: Buttermilk
You can substitute: Milk with lemon juice or yogurt thinned with water
Strange as it sounds, buttermilk is essentially fermented milk, which is made by adding acid to the milk. Create your own version by adding a tablespoon of lemon juice or vinegar to a cup of milk, let it sit for five minutes, then use as the recipe directs. Alternatively, take plain yogurt and thin it with water to form a milk-like liquid.