Homemade Sourdough Onion Rings

Ingredients

• 1 large (softball-sized)yellow onion
• 94 g (¾ cup)plain flour
• 1 tspgarlic powder
• ½ tsp, optionalsmoked paprika
• A generous pinchsalt
• 240 g (1 cup)sourdough discard
• As neededsparkling water or soda water
• 120 g (2 cups)Panko breadcrumbs
• 946 ml (1 US quart)frying oil, such as rapeseed, vegetable or peanut oil
• 120 g (½ cup)mayonnaise
• 60 ml (¼ cup)ketchup
• A few dashes, to tastehot sauce
• Optionalsnipped chives

Instructions

1. 1

   Set up station

   Arrange a shallow tray for the flour, a large bowl for the sourdough batter, and another for the Panko. Set out two baking trays lined with baking paper: one for battered rings and one for breadcrumb-coated rings.

2. 2

   Slice onion

   Trim and peel the onion, then cut it into slices about 1.3 cm thick. Separate the slices into rings, pushing them apart from the centre with your thumbs if needed.

3. 3

   Season flour

   Put the flour, garlic powder, smoked paprika, if using, and a generous pinch of salt in the shallow tray. Whisk together, toss the onion rings in the mixture to coat, then set them aside.

4. 4

   Thin the discard

   Pour the sourdough discard into a large bowl and add a splash of sparkling water or soda water. Aim for a thick pancake-batter consistency that clings to a ring when dipped; adjust with more flour or water if needed.

5. 5

   Prepare breadcrumbs

   Put the Panko breadcrumbs in a separate large bowl.

6. 6

   Dip in batter

   Dip a few floured rings at a time into the sourdough batter, letting excess batter drip off. Place them on one of the lined trays and repeat until all the rings are coated.

7. 7

   Coat with Panko

   Using tongs, coat each ring individually in Panko on both sides, then place it on the second lined tray. Add more breadcrumbs to the bowl as needed.

8. 8

   Heat the oil

   Heat the oil in a heavy-based pot over medium-low heat to 185–190°C. Check with a thermometer; if you do not have one, drop in a pinch of Panko and make sure it sizzles and turns golden.

9. 9

   Fry the rings

   Fry a few rings at a time for about 2–3 minutes, until golden. Transfer them with a slotted spoon to a paper-towel-lined plate and season with salt while hot. Repeat with the remaining rings, allowing the oil to return to 185–190°C between batches and avoiding overcrowding.

10. 10

    Mix the sauce

    Stir together the mayonnaise, ketchup and hot sauce, leaving the chives out for garnish. Chill the sauce until ready to serve.

11. 11

    Serve hot

    Pile the onion rings onto a platter or tray. Serve with the dipping sauce on the side and garnish it with snipped chives if using.

What are sourdough onion rings?

Onion rings are a familiar American diner and takeaway side: sliced onion is coated, crumbed and fried until crisp. This version uses sourdough discard in the batter, a handy way to use starter left over from feeding.

The method builds up separate layers of flour, batter and Panko. That gives the onion a coating with a crunchy finish, while the tangy dip brings a creamy, sharp contrast.

Nutrition and macros by portion

The nutrition label shows one serving as written: 700 calories, 10g protein, 75g carbs, 40g fat.

The onion and flour-based sourdough discard contribute most of the carbohydrates, while the Panko and frying oil add further energy and fat; mayonnaise also makes the dip a significant source of fat. The discard and breadcrumbs provide some protein, though this is not a protein-heavy meal. For a more balanced plate, serve a few rings with a substantial salad or vegetables.

Why the coating has three layers

Flour first: a light coating gives the batter something to cling to. Shake or toss off excess so the rings do not become pasty.

Batter next: thin the discard with sparkling water or soda water until it resembles thick pancake batter. It should coat the onion rather than run straight off.

Panko last: the larger, flaky crumbs create the distinctive crisp outer layer. Coat one ring at a time to keep the crumbs dry and easy to handle.

Get the oil temperature right

A thermometer is the most reliable way to hold the oil at 185–190°C. If it is cooler, the coating can absorb more oil before browning; if it is too hot, it may colour before the onion softens.

The temperature drops when you add a batch. Fry only a few rings at once and let the oil return to temperature between batches.

Look for a golden crust

The rings need about 2–3 minutes in the hot oil. Use the colour and crispness of the Panko as your main cues: the coating should be golden, not pale or dark brown.

Lift the rings out with a slotted spoon and drain them on kitchen paper. Season while they are still hot so the salt adheres.

Keep the preparation orderly

Set up the flour tray, batter bowl, breadcrumb bowl and two lined trays before coating the onion. Keeping each stage in its own place makes it easier to move the rings along without mixing the dry and wet coatings.

Use tongs for the crumb stage, and keep one tray for batter-coated rings and the other for fully crumbed ones. Leave room between coated rings so they are easier to lift.

Serve with a simple dip

The mayonnaise and ketchup make a creamy, tangy dip, with hot sauce to taste. Chives add a fresh finish; keep them for the garnish rather than mixing them into the sauce.

Serve the rings straight after frying while their crust is at its crispest. They work as a snack or side alongside burgers, sandwiches or a simple salad.

Recipe notes & tips

• Cut the onion into evenly thick slices so the rings cook at a similar rate.
• Adjust the discard batter gradually with sparkling water, aiming for a coating that clings.
• Keep the Panko bowl dry by coating the rings one at a time.
• Use a heavy-based pot and do not fill it more than halfway with oil.
• Fry in small batches and restore the oil to 185–190°C between them.
• Season the rings as soon as they come out of the oil.

Variations

• Make it spicier: add extra hot sauce to the dip or a little more smoked paprika to the flour.
• Change the herbs: garnish the dip with finely chopped parsley instead of chives.
• Use a different onion: try a large white or red onion, cut into the same thickness.
• Add more garlic: stir a little extra garlic powder into the flour mixture.
• Choose another dip: serve the rings with a simple barbecue sauce instead of the mayonnaise mixture.

Common mistakes to avoid

• Batter too thin: add a little flour until it clings to the onion ring.
• Coating sliding off: toss the rings in flour first and shake off the excess before dipping.
• Soggy breadcrumbs: coat rings one at a time and keep the Panko bowl free of batter drips.
• Oil temperature dropping: fry fewer rings per batch and let the oil heat back up between batches.
• Crowding the pot: leave space around each ring so the coating fries evenly.
• Dark coating too soon: lower the heat and check that the oil is around 185–190°C.

How to store

For the best crunch, serve the onion rings immediately. Refrigerate leftovers in a covered container for up to 2 days, then reheat in an oven or air fryer until hot and crisp; avoid the microwave, which softens the coating. Store the dip separately in the fridge.

Frequently asked questions