How can I replace buttermilk in baking recipes?

I mix a teaspoon of apple cider vinegar in one cup of a milk alternative like soy or almond. Or you can just use coconut milk if the flavour will go well with what your making.

For each cup of soy milk, add 1 tablespoon of lemon juice or vinegar. After you stir it in, let it stand for ten minutes to "sour". Rice milk does not work as well because of the lower protein content, so I recommend soy milk.

The vegan alternative I always see in recipes is very similar to Tara's suggestion: 1 cup minus 1 tablespoon of soy milk, plus 1 tbsp of vinegar (or apple cider vinegar). It does make it curdle a bit!