Sweet Onion Sauce


Have you ever enjoyed Subway’s Sweet Onion Sauce and wished you could make it yourself?  Now you can, with our delicious copycat recipe.  It’s the Subway sauce that’s sweet, flavorful,  and even addictive. And you can’t buy it anywhere so having an excellent copycat recipe can be invaluable.

Sub sandwich
Sub sandwich

Equipment Needed

Measuring Cup
Stirring Spoon
Airtight Storage Container


Sugar. This sauce has a fair amount of sugar, thus its name. If your dietary restrictions require you to avoid sugar, you can use your favorite one to one sugar replacement for this sauce.

Cornstarch. Arrowroot or all-purpose flour can be substituted for the cornstarch in a pinch. Either one will help to thicken the mixture which is the purpose of the cornstarch.

Vinegar. The vinegar is an important ingredient in the sauce because it helps to add the zing to the flavor.

However, you use apple cider vinegar as a replacement for the red wine vinegar, if necessary, but you’ll want to cut the quantity in half because of its strength. 

Onion flakes. Onion powder can make a substitute for onion flakes in this recipe. We recommend using about 1 teaspoon and then adding more according to your personal preferences.


To store Sweet Onion Sauce, place it in an airtight container in the refrigerator and store sealed. This recipe can potentially be kept for several days to weeks.

However, if any key indicators of spoilage appear, such as mold, a strange smell, discoloration etc. throw the sauce away, and do not risk consuming it.

sweet onion sauce and other sauces
sweet onion sauce and other sauces

Sweet Onion Sauce Ingredients

1 cup Sugar
½ cup Cold water
2 tablespoons Red wine vinegar
5 tablespoons White vinegar
1 tablespoon Cornstarch
¾ teaspoon Minced onion flakes
2 teaspoons Mustard powder
1 tablespoon Dijon mustard
1 tablespoon Fresh onion juice
1 tablespoon Poppy seed
¼ teaspoon Garlic salt
½ teaspoon Onion salt
¼ teaspoon Paprika
¼ teaspoon Pepper
Few drops Sesame oil

Instructions: An Easy Subway Copycat Recipe

Following are step-by-step instructions for making our copycat recipe.

1. Whisk sauce ingredients together in a small saucepan.

2. Bring mixture to boil, stirring consistently.

3. Reduce heat to low and let simmer, stirring until thick.

4. Allow to cool, then serve or store.

5. Enjoy!

What to Serve Sauce With:

Homemade Subway Sweet Onion Copycat Sauce is one of a kind and is delicious on all kinds of food items. Here are some ideas for things to use it on:

homemade subs

Sub sandwich
Sub sandwich

Frequently Asked Questions

Following are frequently asked questions regarding Copycat Subway Sweet Onion Sauce. If you have a question that’s not answered here, please feel free to drop it in the comments box below and we’ll be happy to answer it. 

Is Sweet Onion Sauce keto friendly?

The restaurant version of dressing is quite high sugar. However, the homemade version can be made with artificial sweetener to eliminate sugar.

How long will homemade sauce last?

Homemade sauce can last a few days to a few months, depending on ingredients that were used to make it. If you suspect any indications of spoilage are present, be sure to discard the sauce rather than consuming it.

Is this Sweet Onion Sauce healthy?

As is true with any food, it should be eaten in moderation. And if you have food allergies or dietary restrictions, be sure to substitute ingredients as appropriate.

sweet onion sauce and other sauces
sweet onion sauce and other sauces

What is Subway sweet onion sauce made of?

The restaurant’s nutrition information indicates that it has ingredients that contain sesame, soybeans, and wheat and gluten containing ingredients. For the full list of ingredients, check out their online ingredient guide here.

What does Subway Sweet Onion Sauce taste like?

The sauce tastes as the name indicates. It is a sweet sauce that has a bit of an onion aftertaste. It’s especially delicious on sandwiches and salads. Check out our list of ideas above for ways to use it.

Can you buy Subway Sweet Onion Sauce?

Sadly, Subway doesn’t sell its Sweet Onion Sauce separately. It can only be purchased as a condiment already on your sandwich or in your salad.

If you want some of this delicious sauce outside of those circumstances, we’ve got you covered. 

How many calories in copycat Sweet Onion Sauce?

The following are the estimated nutrition facts for our copycat sweet onion sauce. Please keep in mind that this data is estimated and is based on the ingredients used.  The nutrition facts can vary according to the ingredients used and the brand of ingredients.

Calories 150
Total fat 1.1 g
Saturated Fat 0.1g
Cholesterol 0 mg
Sodium 124 mg
Total Carbohydrates 36g
Dietary. Fiber 0.5g
Total Sugars 33.8g
Protein 0.7g

What sauces does Subway serve? 

According to the Subway website, at the time of this post, Subway offered the following sauces:

Baja Chipotle Southwest Sauce
Barbecue Sauce
Franks Red Hot Buffalo Sauce
Creamy Sriracha
Honey Mustard
Hot Pepper Relish
Lite Mayonnaise
Parmesan Vinaigrette
Oil & Vinegar
Ranch Sauce
Red Wine Vinegar
Roasted Garlic Aioli
Sweet Onion Sauce

Other Sauce Recipes:

Ginger Miso Vinaigrette
Lemon Shallot Dressing
Shallot Mustard Vinaigrette
Pineapple Glaze

Save to Pinterest

For more posts like this one, follow us on PinterestFacebookInstagram and YouTube.

Photo of author
Sarah is known for her extra fancy yeast breads, melt in your mouth pies, and everything salads. She has won awards as a home cook, and is passionate about helping others feel smarter in the kitchen. Sarah is the cooking genius of the sister duo.

Leave a Comment

Recipe Rating