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A pile of yellow onions

Sweet Onion Sauce Recipe

A sweet onion sauce is a delicious and versatile condiment that can be used in place of ketchup or mustard or combined with them for even more flavour.
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Course Condiment
Cuisine British
Calories 583 kcal

Equipment

  • Kitchen scales
  • Chopping board and knife
  • Large saucepan
  • Long-handled spoon for stirring
  • Whisk
  • Ladle
  • Funnel
  • Clean, sterilised glass jars/bottles with sealable lids
  • Optional: squeezy sauce bottles with air-tight caps.

Ingredients
  

  • 150 g onions
  • 2 cloves garlic
  • ½ cup water
  • ½ cup sugar
  • 150 ml vinegar
  • 1 tsp coarse or smooth Dijon mustard paste
  • 1 tsp dried onion powder
  • 1 tsp ground ginger
  • ¼ tsp black pepper
  • ¼ tsp salt
  • 1 lemon
  • 1 tbsp arrowroot or cornflour for the thickening slurry
  • 3 tbsp water for the thickening slurry

Instructions
 

  • Peel the onions and garlic and chop them into rough pieces.
  • Add the onions and garlic to the blender, with the water, and blend well until smooth
  • Now you can pour the smooth onion mixture into the pan.
  • Heat your pan gradually and keep on low heat, stirring regularly.
  • Add the sugar and vinegar and mix well.
  • Also put in the onion powder, ground ginger, salt and pepper. Stir well.
  • Cook the sauce on slow heat until it gets translucent. Make sure to mix with a whisk frequently to avoid burning the mixture.
  • Now, add the lemon juice. Stir through.
  • Dip in a spoon and blow on it to cool, and then taste for seasoning as well as any other adjustments that you would like to make e.g. more sugar if you need it to be sweeter, more lemon/vinegar for a tangier taste, etc.
  • Mix cornflour and water to create a slurry. Do NOT add the cornflour/arrowroot directly to the mixture as you will end up with lumps. When I make the slurry I like to add it slowly, in a couple of teaspoons at a time, stir through and allow to cook on low as adding too much can easily make the mixture too thick. ( If this does happen add some water and whisk vigorously to try to rescue it - overall, it's easier to go slowly and stop when the sauce is thick enough for you.
  • Keep whisking on the heat as the sauce thickens. Finalise your preferred consistency of the sauce being aware that it will thicken further as it cools.
  • When you are satisfied with the consistency ( I like mine similar to a tomato ketchup consistency), use the funnel to transfer the mixture into your very clean containers (or air-tight squeezy sauce bottle).
  • Store in the fridge or freeze in portions to extend its life and availability.
    Thaw it in the fridge when you want to use it. Use cold, at room temperature or gently heated in the microwave.

Notes

TIPS for making this sweet onion condiment

If you're planning to make some sweet onion sauce, here are some tips to help you on this adventure:
1. Choose suitable onion.
When it comes to sweet onion sauce, you want to ideally use a sweet onion like a Supasweet, Ailsa Craig, or Walla walla varieties. These onions have a naturally sweet mild onion taste, which will give your sauce its signature flavour. Shallots, with their milder flavour, can be a useful alternative.
2. Caramelize the onions.
One of the keys to making a great sweet onion sauce, for me, is to caramelize the onions by cooking them slowly on low heat. This will help to bring out their natural sweetness and give the sauce a rich, deep flavour. This is even more important if you are using a different type of onion as those with sharper stronger flavours will need their natural sugars coaxed out gently. So you can either chop up the onions and caramelise them, let them cool for a while and blend until smooth with the garlic and water. Then I return this to the pan, add the rest of the ingredients and follow the recipe till completion.
In the recipe , I have listed the faster, more straightforward option, which is to blend the raw onions with the garlic and water at the beginning and then just work through the rest of the recipe. You may want to try both versions and see which you prefer! This is part of the fun of making this yourself.
3. Add acidity.
To balance out the sweetness of the onions, you'll need to add some acidity to your onion sauce recipe. You achieve this by adding vinegar and lemon juice. You adjust the amount of lemon juice relative to how sweet or tangy you like your sauce.
4. Don't forget the salt.
This will help to round out the flavours and make sure that your sauce is perfectly seasoned.
 

Flavouring options for sweet onion sauce

    • A pinch, or more, of hot chilli powder for a spicy kick.
    • Orange/lime/lemon zest for a sharp, fresh boost.
    • Add some herbs to the blender with the onions and garlic for a fragrant taste note e.g. fresh coriander.
 

Using this delicious sauce

1. As a member of the staple condiment range used on burgers or hot dogs - either on its own or in combination with the tomato ketchup and/or mustard sauce.
2. As a dip for chicken nuggets or onion rings.
3. Mix some sweet onion sauce with mayonnaise and use it as a dressing for salads
4. Bring something new to a potato salad for a novel flavour boost.
5. Drizzled over grilled cheese sandwiches.
6. Swirled into mashed potatoes or through simple steamed vegetables.
7. Use as a topping for pizza.
For more information see RESOURCES and RECIPES.
 

Nutrition

Calories: 583kcalCarbohydrates: 142gProtein: 4gFat: 1gSaturated Fat: 0.2gPolyunsaturated Fat: 0.2gMonounsaturated Fat: 0.2gSodium: 670mgPotassium: 460mgFiber: 7gSugar: 115gVitamin A: 34IUVitamin C: 71mgCalcium: 108mgIron: 2mg
Nutritional Disclaimer

All nutritional information is an estimate only, based on third-party calculations derived from an online nutritional calculator, Spoonacular API. The data provided is a courtesy and should not be considered a guarantee or fact. Each recipe and nutritional value will vary depending on the ingredients and brands you use, your measuring methods and portion sizes. For accurate results, we recommend that you calculate the nutritional information yourself, using a preferred nutritional calculator or advice from a nutritionist, based on your ingredients and individual processes.

Keyword sweet onion sauce
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