Sourdough Onion Rings
Sourdough onion rings are an easy and delicious way to use your sourdough starter discard! Crispy, crunchy, and oh so tasty, serve these treats as a snack, appetizer or side dish!


Ah, sourdough discard. Is there anything it can’t do? I mean, yeah, an active starter is pretty amazing for bread, but there is SO much more to sourdough that just bread!
I love that the yeast and signature sourdough tang bring so much to so many recipes – like extra flakey sourdough pie crust, the richest sourdough brownies you have ever tasted, and the amazing depth of flavor in chocolate sourdough cake.
Check out my sourdough recipe page for over 60 sourdough recipes (for discard and active starter). You are going to want to make them all!
New to sourdough? Read my ultimate guide to sourdough for beginners to get all the answers to your questions in easy to understand ways!
Using your sourdough starter as the base of a batter to fry with is really fun and delicious. The lactic acid and acetic acid the yeasts naturally produce helps to really deepen the flavor and create this lovely tang that is amazing in onion rings. Plus the batter does a great job of staying crispy, even after the onion rings cool.
You are going to want to create excess sourdough discard specifically to make sourdough onion rings with! They are THAT good!
Other fried sourdough recipes:
How to make onion rings with sourdough discard
These onion rings are easy to make, so you can enjoy them as often as you want! For the full set of directions, make sure you scroll down to the recipe card below. Here is a brief overview of how to make these sourdough onion rings:
- Peel and slice the yellow onions into slices.
- Stir the dry ingredients together until well blended.
- In a medium sized bowl, whisk together the sourdough starter and cold sparkling water.
- Pour enough oil into a deep Dutch oven or a cast iron skillet so it is about 1 1/2 inches deep. Place a wire rack on a rimmed baking sheet.
- Heat the oil until it reaches 375°F.
- Once the oil has reached temperature, dip an onion ring in the sourdough starter mixture until it is coated, and then coat in the flour mixture.
- Fry the rings for about 1 1/2 to 2 minutes, then flip the rings over with tongs and continue to fry until the rings are golden brown, an additional 1 1/2 to 2 minutes.
- Move the fried onion rings to the wire rack, and repeat with the remaining onion rings.
- Once all the onion rings are fried, sprinkle with extra salt and serve warm with your favorite condiment.
Frying Tips
Don’t be intimidated by frying! It’s not hard, and you can do it!
What pan to use
You want a cooking vessel that is heavy, and stable and both wide and deep. A deep cast iron skillet is a great option.
What oil to use
The oil you use for frying should be clear, relatively flavorless, and should be able to be heated to high temperatures without smoking. When a hot oil starts smoking, it starts breaking down, and you don’t want that while you are cooking with it.
Good choices are peanut oil, safflower oil, sunflower oil, and canola oil. Olive oil is not a good choice for frying as it starts smoking at lower temperatures.
For this recipe, we need about 1 1/2″ of oil in the bottom of your pan.
Getting the oil hot enough
Place the oil in the cold pan and turn it on to medium-high heat. Getting the oil hot and keeping it at that temperature is important for correctly fried foods that are moist and tender inside and golden and crispy outside.
- Oil that is too hot will burn the outside while not cooking the inside.
- Oil that is not hot enough will cause the apple rings to cook too slowly, and it will absorb too much oil, which makes it taste not as good and also have a greasy mouth feel.
You want to heat the oil to 365°–375°F. Use a deep fat frying thermometer to monitor the temperature while you cook.
Frequently Asked Questions
What kind of sourdough do I need for this recipe?
This recipe uses a sourdough starter that is at a 100% hydration. You can either use a fed and active starter, or you can discard. For reference on how to properly feed your sourdough starter and how to know when it is active, read the article Feeding Your Sourdough Starter.
The starter should be at room temperature when you use it for this recipe, as that helps it to mix into the cake batter better.
Why won’t my batter stick to my onion rings?
Its important to make sure that the batter is cold. If as you make batches of onion rings you notice that it isn’t sticking as well,
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Sourdough Onion Rings Recipe
Equipment
Ingredients
- 3 large yellow sweet onions
- 2 cups 100% hydration sourdough starter discard
- 1 cup all-purpose flour
- ½ cup cold sparkling water
- 1 ½ teaspoons kosher salt
- 1 teaspoon garlic powder
- 1 teaspoon ground mustard
- ½ teaspoon black pepper
- ½ teaspoon smoked paprika
- Cooking oil for frying like peanut avocado, or rice bran
To serve
- Extra salt for finish
- Condiment of your choice like ketchup BBQ sauce, blue cheese or ranch dressing
Instructions
- Peel and slice the yellow onions into 3/4-inch thick slices. If you prefer your onion ring thinner or thicker, feel free to slice it the size of your preference. Keep in mind that thinner rings will cook faster and thicker rings will take longer to cook. Separate the slices into rings, saving the smaller inner rings for a different use.
- Place the flour, garlic powder, pepper, and paprika in a large shallow bowl or baking dish. Use a whisk and stir the dry ingredients together until well blended.
- In a medium sized bowl, whisk together the sourdough starter and cold sparkling water.
- Pour enough oil into a deep Dutch oven or a cast iron skillet so it is about 1 1/2 inches deep. Keep in mind the oil will bubble up a lot, so if you aren’t familiar with deep frying, a Dutch oven is your best option. Place a wire rack on a rimmed baking sheet.
- Heat the oil until it reaches 375°F. If you don’t have a candy/deep frying thermometer or a quick read thermometer, place a 1-inch cube of bread in the oil. The cube should turn golden brown in 60 seconds.
- Once the oil has reached temperature, dip an onion ring in the sourdough starter mixture until it is coated.
- Move the ring with a fork to the flour mixture and toss to coat. Do this with three or four onion rings. As the flour mixture starts to clump up because of starter liquid drippings, just rub the clumps between your fingers to break them up into smaller bits.
- Fry the rings in the oil by placing a ring partially in the oil, then letting go. The onion ring will slide into the oil without splashing. Do not drop the ring into the oil from the air! This will cause the oil to splash up and splatter, potentially burning you. Don’t over crowd the pan, just fry in small batches. This will make sure the oil doesn’t drop in temperature too fast.
- Fry the rings for about 1 1/2 to 2 minutes, then flip the rings over with tongs and continue to fry until the rings are golden brown, an additional 1 1/2 to 2 minutes.
- Move the fried onion rings to the wire rack, and repeat with the remaining onion rings, coating first with the sourdough starter, then the flour, then frying.
- Once all the onion rings are fried, sprinkle with extra salt and serve warm with your favorite condiment.
Could these be cooked in an air fryer instead? Thanks!
Hi Kate! I haven’t done it (I don’t have an air fryer yet!), but I am sure you could!