featured 17527

Subway Sweet Onion Sauce: Flavor, Ingredients & How It’s Made

Copycat version of Subway’s sweet onion sauce. Now you can enjoy the sweet, tangy sauce on sandwiches and salads at home!

A small glass bottle filled with brown copycat subway sweet onion sauce is in focus. A sliced and unsliced onion are out of focus in the background.

I was disappointed when Subway discontinued their sweet onion sauce. Its blend of tangy vinegar, sweetness, poppy seeds and fresh onion was the perfect complement to sandwiches and salads.

Determined not to lose that flavor, I recreated a homemade version to keep in the fridge. It’s simple to make and ready to drizzle over whatever you like in minutes.

Close up of a glass bottle filled with brown subway sweet onion sauce. You can see the poppyseeds suspended throughout the sauce.

The recipe is very forgiving. You’ll need a way to grate the onion (a cheese grater or microplane works best) and a small saucepan to cook the ingredients together. After a brief boil and a short simmer, let the sauce cool so the flavors meld — a few hours makes it taste best.

Ingredients

All the ingredients to make sweet onion sauce on a black background. Sugar, spice bottles, vinegar bottles, a sweet onion, mustard, and cornstarch.
  • Sugar – Granulated white sugar is the base; you can reduce it by up to 1/3 cup to taste.
  • Vinegar – A combination of white and red wine vinegar provides the bright tang.
  • Onion – Fresh grated sweet onion gives the best flavor. A white onion can be used as a substitute.
  • Sesame Oil – A small amount adds richness and depth.
  • Mustard – Dijon mustard pairs well with the other flavors.
  • Mustard Powder – If you don’t have mustard powder, increase the Dijon by a teaspoon.
  • Spices – Onion powder, garlic powder, paprika, celery seed, poppy seeds, salt, and black pepper.
  • Cornstarch – Thickens the sauce. Arrowroot can be used instead if preferred.

Tips

  1. The sauce can be used as soon as it cools, but it tastes best after several hours when the flavors have fully melded.
  2. Grate the onion using the small holes of a cheese grater, a microplane, or press it through a garlic press. If needed, finely mince the onion.
  3. For a spicy variation, add red pepper flakes or a pinch of cayenne.

What To Use It On

  • Sandwiches
  • Salads
  • Pizza
  • Shredded or baked chicken
  • Roasted or steamed vegetables

Have other ideas for where to use this sweet onion sauce? Share your favorites in the comments.

Copycat sweet onion sauce being poured out of the bottle onto a ham sandwich.

How To Store

Store the sauce in an airtight container in the refrigerator for up to one week. Small glass bottles or squeeze bottles work well for easy dispensing.

Subway Sweet Onion Sauce

A homemade version of the tangy, sweet onion sauce once offered at Subway.
A small glass bottle filled with brown copycat subway sweet onion sauce is in focus. A sliced and unsliced onion are out of focus in the background.
Prep Time: 5 minutes
Cook Time: 10 minutes

Ingredients

  • 1 Cup Sugar
  • 1/2 Cup Water
  • 6 Tablespoons White Vinegar
  • 1 1/2 Tablespoons Red Wine Vinegar
  • 1/2 Tablespoon Onion, freshly grated
  • 1 Tablespoon Cornstarch
  • 2 Teaspoons Dijon Mustard
  • 2 Teaspoons Mustard Powder
  • 1 Teaspoon Poppy Seeds
  • 1/2 Teaspoon Sesame Oil
  • 1/2 Teaspoon Onion Powder
  • 1/2 Teaspoon Salt
  • 1/4 Teaspoon Garlic Powder
  • 1/4 Teaspoon Celery Seed
  • 1/4 Teaspoon Paprika
  • 1/4 Teaspoon Black Pepper

Instructions

  • Combine all ingredients in a small saucepan. Whisk constantly while bringing the mixture to a boil.
  • Boil for 5 minutes, then reduce to a simmer and continue whisking for another 5 minutes until the sauce thickens.
  • Remove from heat and allow the sauce to cool. The texture will set as it cools.
  • Transfer to an airtight container and refrigerate for up to one week.

Author: Jessica Pinney