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Nov 29, 2023

Three-Ingredient Sourdough Onion Rings

These sourdough onion rings, with just three ingredients, will satisfy your craving for one of the best diner or coffee shop sides ever invented. 

Stack of Three-Ingredient Sourdough Onion Rings.

If you love onion rings as much as I do, this three-ingredient onion ring recipe will satisfy your craving when you can't get to your favorite diner, deli, or coffee shop. 

In fact, these onion rings, made with just sourdough starter, onions, and oil, have that sourdough tang that you'll never taste in a restaurant onion ring. 

Three-Ingredient Sourdough Onion Rings in a bowl with dipping sauces.

I grew up in the era of malt shops, diners, and drive-ins. One of my favorite things to do after school was to go to a malt shop and get a basket of onion rings to share with my friends. They were magical. 

Deep frying has always intimidated me, so my first attempt at onion rings involved oven frying. The results were amazing, and I highly recommend the recipe. However, the recipe is pretty involved. 

Because I already maintain a sourdough starter for my bread baking hobby, I was intrigued with the idea of using the discard for onion rings. I'm completely thrilled with the results. 

Three-Ingredient Sourdough Onion Rings Stacked.


Onions: You can use brown, yellow, white, or sweet onions. I use a sweet onion. 

Sourdough Starter Discard: I use a 100 percent hydration sourdough starter. What that means is that the starter is fed with equal parts flour and water, by weight (not volume). 

Oil for Frying: Use a neutral oil with a high smoke point, meaning it can be heated to a high temperature without burning. Oils with a high smoke point include avocado oil (the highest), peanut oil, safflower oil, soybean oil, canola oil, or corn oil. 

Once the onion rings are cooked, sprinkle them with salt and serve them with your favorite ketchup and/or dipping sauce. 

Three-Ingredient Sourdough Onion Rings with two dipping sauces.

How to Make Sourdough Onion Rings:

First, slice onions into 1/2 inch or slightly smaller slices and separate the rings. 

Next, heat about two to three inches of neutral oil to 375 degrees F. 

After that, dip the sliced onions into a bowl of sourdough starter and fry them in batches until they are browned and puffy. 

Finally, drain the cooked onion rings on paper towel lined sheet pans in a 200 degree F oven to keep them warm. 

Onions for Onion Rings on a Cutting Board.

Equipment You May Need:

I used a mini deep fryer that I have for frying these onions to fry them in batches. I love it because you don't have to worry too much about controlling the burner on your stove. You can also use a Dutch oven or wok for frying and a candy thermometer to monitor the temperature of the oil. 

You'll also need a half sheet pan for "holding" the onion rings in the oven. 

My favorite tool for flipping and straining these onion rings is a spider strainer

Suggested Dipping Sauces:

Ketchup (my favorite)

Ranch Dressing

Blue Cheese Dressing

Roquefort Dressing

Sourdough Onion Ring Recipe Variations:

While I just salted these onion rings after frying, you can include additional salt into the batter. You can also add additional spices such as black pepper, paprika, ground mustard, Creole seasoning, or garlic powder to the batter before dipping in the onions. 

I tried dipping the onions into flour before the starter, but I found that it wasn't necessary. Just dip and fry! Of course, you could add breading too, but I love these as they are. 

Evidently, the secret sauce to the success of using just the batter is the fact that the batter has had a chance to really develop the gluten in the wheat. This helps it stay together in the hot oil. No egg is necessary. 

Three-Ingredient Sourdough Onion Rings with two dipping sauces.

Tips for Success:

This recipe is designed for using leftover sourdough starter. My starter hadn't been fed in about two weeks. You can experiment with the amount of time it takes before the starter is no longer good for these onion rings, but I suspect the time is much longer. 

If you're really concerned, stir in a small amount of baking soda to the sourdough discard before dipping the onion rings. 

For Leftovers:

Do not try reheating leftovers in the microwave. 

Drain any leftover onion rings on a paper towel lined plate and refrigerate. Reheat them in an air fryer or convection oven. You'll love the results. 

Three-Ingredient Sourdough Onion Rings in a red checkered paper lined bowl.

More Fun Snack Recipes:

Oven Baked Garlic Fries

Baked Zucchini Fries

Delicata Squash Fries

Homemade Ding Dongs

Olive Garden Breadsticks (copycat)

El Pollo Loco Chicken Tortilla Soup

Tempura Onion Rings

Sourdough Onion Rings

Sourdough Onion Rings
Yield: 4 servings
Author: Karen's Kitchen Stories
Prep time: 10 MinCook time: 5 MinTotal time: 15 Min
These sourdough onion rings, with just three ingredients, will satisfy your craving for one of the best diner or coffee shop sides ever invented.


  • 1 large brown, yellow, or sweet onion
  • Vegetable or other neutral oil
  • 1 to 2 cups of 100 percent hydration sourdough starter in a bowl
  • salt to taste


  1. Peel the onion and slice it into 1/2 inch slices. Separate the rings.
  2. Heat about 2 to 3 inches of oil in a deep fryer, wok, or tall-sided Dutch oven to 375 degrees F.
  3. Place a half sheet pan in your oven and heat the oven to 200 degrees F.
  4. Line a plate with a few layers of paper towels.
  5. Dip each onion ring into the sourdough starter and drop them into the hot oil in batches. Fry for about a minute, and then flip them over. Cook until golden. Lift them out of the oil with a spider strainer and drain them on the paper towel lined plate. Slide them into the oven on the half sheet pan while frying the rest of the onions.
  6. Sprinkle with salt to taste and serve with your favorite dipping sauce.
  7. Refrigerate leftovers and reheat in an air fryer or on a rack in a convection oven at 350 degrees F .

Nutrition Facts



Fat (grams)

7 g

Sat. Fat (grams)

1 g

Carbs (grams)

18 g

Fiber (grams)

1 g

Net carbs

17 g

Sugar (grams)

4 g

Protein (grams)

2 g

Cholesterol (grams)

0 mg
onion rings
side dish
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Would you like to comment?

  1. What a great way to use extra starter! They look fabulous.

  2. These were exactly the kind of onion ring I've been craving! And how easy they were to make! Even more delicious than the ease! Now I need to no longer go out when I have the onion ring craving. Within a few minutes I can whip up the most delicious Rings I've had in a while! Thank you!!!

    1. Thanks! It's pretty mind blowing, isn't it =)


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