How to Convert Any Recipe to Sourdough (The 1:1:1 Ratio)

So you want to know how to convert a recipe to sourdough, but to do this successfully, it helps to understand why recipe substitutions flop. We’ve all been there: you’re halfway through a recipe only to realize you’re out of buttermilk, or perhaps you’ve tried a dairy-free swap that resulted in a bitter or “soapy” tasting disaster. I used to wonder the reason some ingredient swaps worked, and others failed.

It turns out, that reason is chemistry.

Whether you are a sourdough enthusiast just looking to use up discard or a vegan baker struggling with dairy substitutes, there is a universal rule that will “sourdough-ize” almost any recipe containing flour and liquid.

Soapy-tasting Chemistry: Why Recipes Fail

I’ll never forget my first attempt at vegan biscuits. I swapped butter for margarine and buttermilk for unsweetened almond milk, following a standard recipe. The result? They were dry, dense, and had a bitter, strangely soapy aftertaste.

My mom suggested I hadn’t mixed them enough, thinking there were “pockets” of baking soda. But I knew my mixing wasn’t the issue.

The Baking Soda and Vinegar Principle

Remember the classic volcano science experiment? When you mix baking soda (a base) and vinegar (an acid), it bubbles violently. That is exactly how baking soda works in your oven.

The baking soda reacts with an acidic ingredient in your dough to create carbon dioxide gas. Those gas bubbles get trapped in the dough and expand in the heat, giving you lift. If your recipe lacks acid—like swapping out acidic buttermilk for neutral plant milks—the baking soda never fully activates. You’re left with a flat biscuit and a bitter, “soapy” flavor from the unreacted baking soda.

The Sourdough Substitution Solution

You don’t need to be vegan to use this trick, and you don’t even need to be making bread. If a recipe uses flour and liquid, you can sourdough-ize it.

Sourdough starter (whether active or discard) is naturally acidic. It provides the perfect “kick” to activate baking soda, replacing the need for buttermilk, yogurt, sour cream or vinegar.

The 1:1:1 Sourdough Conversion Rule

To keep your recipe balanced, use this golden ratio for substitution:

The Golden Rule: Sourdough starter is generally equal parts flour and water by weight. Therefore, when you add starter, you must subtract equal parts flour and liquid from the original recipe.

The Math in Practice:

If your favorite muffin recipe calls for 2 cups of flour and 1 cup of milk, and you want to use 1 cup of sourdough starter:

• The Flour: Subtract 1 cup. You now need 1 cup of flour.
• The Liquid: Subtract 1 cup. You no longer need any milk.
• The Result: You have successfully “sourdough-ized” the recipe while keeping the hydration levels the same.

Pro-Tip: The 48-Hour Starter Window

While you can use “discard” that’s been sitting in the back of the fridge for a week, this method works best if your starter has been fed within the last 48 hours. A relatively fresh starter has a more balanced acidity and a cleaner flavor profile, ensuring your pancakes, biscuits, or cakes rise high without becoming too tangy. I admit at times I have used some pretty starved sourdough for this method and it made my baked goods taste like I had added vinegar or lots of lemon juice to the recipe.

Quick rule of thumb: If your sourdough smells sharp like vinegar, don’t use it until it’s been fed. If it still smells yeasty and pleasant it’s fine to use.

Why This Revolutionized My Kitchen

• It helps me use all my sourdough discard, so there is no waste.
• I can make fantastic vegan baked goods for friends and potlucks without buying specialty ingredients.
• It’s also the ultimate “oops” button—if you run out of milk or buttermilk, your sourdough starter is standing by to save the day.

“As he that taketh away a garment in cold weather, and as vinegar upon nitre, so is he that singeth songs to an heavy heart.”

Proverbs 25:20

Note: “nitre” = baking soda

What’s one ‘non-bread’ recipe you’ve always wanted to try with sourdough? I’ve found it works in everything from brownies to pizza crust—let’s troubleshoot your favorite recipe in the comments!