If you love Subway’s sweet onion sauce, you’ll be delighted to find we’ve discovered the secret! This tasty condiment transforms every sandwich into a flavor sensation, thanks to a delicate and fantastic balance of sweet and savory.

Don’t be put off by the extensive ingredient list. This sauce is ready in minutes and will keep in the refrigerator for up to one month.

Table of Contents

What is Subway’s Sweet Onion Sauce?

The popular sandwich franchise offered this condiment sauce at its restaurants. However, the chain has replaced this sauce recently with a newer version, known as Teriyaki Sweet Onion.

What is Sweet Onion Sauce Made Of?

Subway’s famous sauce contains onion powder, garlic powder, paprika, dijon mustard, poppy seeds, celery seeds, vinegar, water, and sugar.

Ingredients You’ll Need

Here’s what you will need to make Subway’s famous sauce:

Sugar: This is what puts the “sweet” in sweet onion sauce.
Onion: To ensure you get a smooth sauce, use finely grated onion. We recommend grating it with a small rasp grater to get the right consistency.
Vinegar: To balance the sweetness of the sugar, we use classic white vinegar.
Red wine vinegar: This ingredient has a slightly different flavor profile to its white cousin and works well in this recipe.
Dijon mustard: With its smooth consistency and spicy tang, there’s no better mustard for this sauce.
Sesame oil: You will only need ¼ teaspoon, and you can use either regular sesame oil or toasted.
Seasonings: These elements bring everything together and provide the “cherry” on the cake. You will need dry mustard powder, salt, poppy seeds, celery seeds, onion powder, paprika, black pepper, and garlic powder.
Water: We use water to thin the sauce if it seems too thick or concentrated. Add at your discretion.

(Note: Full recipe is at the bottom of the post)

How to Make Subway Sweet Onion Sauce

In a small microwaveable bowl, add the sugar and water.
For one minute, microwave on full power, whisking several times until dissolved.
Toss in the rest of the ingredients and whisk until combined.
If you find the mixture is too thick, add a few drops of water and whisk to combine. If the mixture is quite thin, you may add a dash of onion powder and mustard powder.
Store in a mason jar in the fridge for up to one month. Use on sandwiches, burgers, and in other recipes.

Is Subway Sweet Onion Sauce Healthy?

Unfortunately, sweet onion sauce contains a lot of sugar and is not considered healthy. One serving contains about 8 grams (or 2 teaspoons) of sugar. We recommend eating it in moderation as part of a balanced diet.

Is Sweet Onion Sauce Keto-Friendly?

If you make this sauce at home, you can substitute the sugar with sweetener. It will then be suitable as part of a keto eating plan.

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Subway Sweet Onion Sauce Recipe

Prep Time 10

Cook Time 6

Total Time 6 10

Servings

Ingredients

¼ cup sugar granulated
¼ cup water
¼ cup white vinegar
1 tablespoon sweet yellow onion finely grated or pressed
1 tablespoon red wine vinegar
1 tablespoon onion powder
½ teaspoon garlic powder
2 teaspoons dijon mustard
2 teaspoons mustard powder
½ teaspoon paprika
¾ teaspoon celery salt
1 teaspoon poppy seeds
¼ teaspoon sesame oil optional
salt and pepper to taste

Instructions

In a small microwaveable bowl, add the sugar and water.
For one minute, microwave on full power, whisking several times until dissolved.
Toss in the rest of the ingredients and whisk until combined.
If you find the mixture is too thick, add a few drops of water and whisk to combine. If the mixture is quite thin, you may add a dash of onion powder and mustard powder.
Store in a mason jar in the fridge for up to one month. Use on sandwiches, burgers, and in other recipes.

Notes

If stored correctly (in a sealed container or jar in the fridge), this sauce will last up to one month.
You can also make sweet onion sauce keto-friendly by substituting the sugar with a low-carb sweetener, where 1 cup of sweetener is equivalent to 1 cup of sugar.