How to Make the Best Sourdough Discard Onion Rings You Will Ever Have with Lemon Aioli and Parmesan.

These sourdough discard onion rings are perfectly crisp, light and flavourful. Serve as a snack, appetizer or side dish, they are sure to be a hit at any table. We pair our onion rings with lemon aioli and a sprinkling of parmesan cheese. Absolutely delicious, we can’t wait for you to give them a try!

sourdough discard onion rings

What You’ll Need:

  • Cutting board
  • Chef’s knife
  • Mixing Bowl
  • Whisk
  • Digital thermometer
  • Heavy dutch oven for frying
  • Slotted spoon
  • Plate lined with paper towel to drain the onion rings after frying

Ingredients:

For the Sourdough Discard Onion Rings Batter:

  • 100g cornstarch
  • 50g all-purpose flour
  • 75g sourdough discard
  • 1 pinch salt
  • 200ml sparkling cold water

For the Lemon Aioli:

  • 1 lemon, juiced and zested
  • 1 tsp Frank’s Hot sauce
  • I tbsp dijon mustard
  • 1 egg yolk
  • 1 cup of grape seed oil
  • 1 clove of garlic
  • 1 Pinch of salt
  • 1/4 tsp cracked black pepper
Lemon Aioli Mise en Place

Additional Ingredients:

  • Grapeseed oil for frying (or another high heat cooking oil such as vegetable or canola oil)
  • Parmigiano Reggiano
  • 2 Medium sweet onions such as Vidalia onions.

Note: To cut your onion rings, peel the onion and cut them into 1.25cm / 1/2inch rings. Separate the onion into rings. I like to keep the larger ones separate from the small ones as both sizes will have slightly different cooking times.

If you’d like to cut down on the onion flavour you can soak the onion rings in buttermilk or whole milk overnight before frying. Keep in mind this will make your sourdough onion rings a little heavier.

Instructions:

For the Sourdough Discard Onion Ring Batter:

  1. Mix the cornstarch, flour and salt together. 
  2. Add the sourdough discard and mix lightly.
  3. While mixing, pour in the sparkling water and continue to mix until it resembles a pancake batter.
  4. Let the batter rest for 20 minutes before using.
The sourdough discard onion ring batter just before using.

To Fry the Sourdough Discard Onion Rings:

  1. Heat the oil to 365-395°F (185-200°C) in a heavy bottom cast iron skillet or dutch oven. 
  2. Lightly coat the onions in the batter allowing the excess to drip off. 
  3. Gently place the onions into the frying oil and let them fry for 3-4 minutes on each side. 
  4. Remove the onions when they are golden brown from the pan and place them onto a paper towel.
  5. Season with salt while warm. 
Thermapen

Notes: Use a thermometer to check the frying temperature. Keep in mind that the more you put into the fryer the more the temperature will fluctuate hence the wide range in the instructions.

When frying, we like to use a heavy cast iron pot. My go to is the Smithey Dutch Oven, but any heavy dutch oven will work. You can also shallow fry them in a skillet but keep in mind the temperature will fluctuate much more with less oil, so pay close attention to your temperatures!

The colour of the onion rings should be a perfect golden brown when done frying. The batter is meant to be light and crisp and coat the onions. If you notice your onions are cooking too fast you can turn the oil down.

For the Lemon Aioli:

  1. Add the egg yolk, salt, Frank’s hot sauce, salt, lemon juice, pepper and dijon mustard to the bowl.
  2. Finely rasp the garlic with a microplane and add it to the bowl.
  3. Whisk together until light and well combined.
  4. Slowly drizzle in the oil while whisking the mixture.
  5. Once you have added all the oil, check the aioli for consistency. If it is not thick enough you can continue to add more oil until desired consistency.

Notes: The aioli is an emulsion of oil and the rest of the ingredients. The egg yolk and the dijon contain lecithin which help bind the two together. Every cook splits an aioli from time to time. While many throw it away and start again, there are a few tricks you can do to fix a broken emulsion.

If the aioli splits while you are making it there are a few ways you can fix it. One way is to add a few drops of warm water and continue whisking. If this doesn’t work you can start the emulsion again. Place a new egg yolk in a bowl with a tsp of dijon. Whisk the egg and dijon together. Start to stream in the broken mixture whisking vigourously.

Aioli Variations:

  • Tarragon Aioli – Mix in some chopped tarragon after making your aioli.
  • Roasted Garlic Aioli – Replace the fresh garlic with roasted garlic. You an also use garlic oil to make the emulsion.
  • Chili Aioli – Add in a few chopped chillies or chilli paste at the beginning of making your aioli.
  • Cilantro and Lime Aioli – Replace the lemon juice with lime juice and add chopped cilantro after making the emulsion.

To Serve:

Put the sourdough discard onion rings on a plate and the lemon aioli into a serving bowl. Grate parmesan cheese over the onion rings and while warm so the cheese sticks to the onions rings and serve warm.

Sourdough Discard Onion Rings Recipe Card:

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sourdough discard onion rings

How to Make the Best Sourdough Discard Onion Rings You Will Ever Have.

  • Author: Matthew James Duffy
  • Prep Time: 20 minutes
  • Cook Time: 20 minutes
  • Total Time: 40 minutes
  • Yield: 2 servings 1x
  • Category: Sourdough Discard
  • Method: Deep Frying

Description

These sourdough discard onion rings are perfectly crisp, light and flavourful. Serve as a snack, appetizer or side dish, they are sure to be a hit at any table. We pair our onion rings with lemon aioli and a sprinkling of parmesan cheese. Absolutely delicious, we can’t wait for you to give them a try!


Scale

Ingredients

For the Sourdough Discard Onion Rings Batter:

  • 100g cornstarch
  • 50g all-purpose flour
  • 75g sourdough discard
  • 1 pinch salt
  • 200ml sparkling cold water

For the Lemon Aioli:

  • 1 lemon, juiced and zested
  • 1 tsp Frank’s Hot sauce
  • I tbsp dijon mustard
  • 1 egg yolk 
  • 1 cup of grape seed oil
  • 1 clove of garlic
  • 1 Pinch of salt
  • 1/4 tsp cracked black pepper

Additional Ingredients:

  • Grapeseed oil for frying (or another high heat cooking oil)
  • Parmigiano Reggiano
  • 2 Medium sweet onions such as Vidalia onions.

Instructions

For the Sourdough Discard Onion Ring Batter:

  1. Mix the cornstarch, flour and salt together. 
  2. Add the sourdough discard and mix lightly.
  3. While mixing, pour in the sparkling water and continue to mix until it resembles a pancake batter.
  4. Let the batter rest for 20 minutes before using.

To Fry the Sourdough Discard Onion Rings:

  1. Heat the oil to 365-395°F (185-200°C) in a heavy bottom cast iron skillet or dutch oven. 
  2. Lightly coat the onions in the batter allowing the excess to drip off. 
  3. Gently place the onions into the hot oil and let them fry for 3-4 minutes on each side. 
  4. Remove the onions when they are golden brown from the pan and place them onto a paper towel.
  5. Season with salt while warm. 

For the Lemon Aioli:

  1. Add the egg yolk, salt, Frank’s hot sauce, salt, lemon juice, pepper and dijon mustard to the bowl. 
  2. Finely rasp the garlic with a microplane and add it to the bowl. 
  3. Whisk together until light and well combined. 
  4. Slowly drizzle in the oil while whisking the mixture. 
  5. Once you have added all the oil, check the aioli for consistency. If it is not thick enough you can continue to add more oil until desired consistency.

To Serve:

  • Put the sourdough discard onion rings on a plate and the lemon aioli into a serving bowl. Grate parmesan cheese over the onion rings and while warm so the cheese sticks to the onions rings and serve warm. 

Notes

For the OnionsTo cut your onion rings, peel the onion and cut them into 1.25cm / 1/2inch rings. Separate the onion into rings. I like to keep the larger ones separate from the small ones as both sizes will have slightly different cooking times.

For Frying: Use a thermometer to check the frying temperature. Keep in mind that the more you put into the fryer the more the temperature will fluctuate hence the wide range in the instructions.  When frying, we like to use a heavy cast iron pot. My go to is the Smithey Dutch Oven, but any heavy dutch oven will work. You can also shallow fry them in a skillet but keep in mind the temperature will fluctuate much more with less oil, so pay close attention to your temperatures!

For the Aioli: The aioli is an emulsion of oil and the rest of the ingredients. The egg yolk and the dijon contain lecithin which help bind the two together. Every cook splits an aioli from time to time. While many throw it away and start again, there are a few tricks you can do to fix a broken emulsion.  If the aioli splits while you are making it there are a few ways you can fix it. One way is to add a few drops of warm water and continue whisking. If this doesn’t work you can start the emulsion again. Place a new egg yolk in a bowl with a tsp of dijon. Whisk the egg and dijon together. Start to stream in the broken mixture whisking vigourously.

If you liked this recipe for sourdough discard onion rings, check out our other sourdough discard recipes for sourdough discard ricotta gnocchi and sourdough discard tempura battered squash blossoms.

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