Store-bought buttermilk will work fabulously in this basic cornmeal recipe, but you can just as easily make it at home using just two simple ingredients. Mix one and a half tablespoons of vinegar or lemon juice in a cup and a half of milk. Stir the mixture and let it sit for about 5–10 minutes. The milk will thicken slightly and may look a bit curdled—that’s your homemade buttermilk! Whisk before you add it to the batter.