When Subway discontinued their iconic sweet onion sauce, I made it my mission to recreate it. This wasn’t just any sauce—it was the one that made every sandwich unforgettable. After countless kitchen experiments and many willing taste-testers, I finally cracked the code to capturing that perfect balance of sweet, tangy, and savory flavors.
Why You’ll Love This Sweet Onion Sauce
- It takes just minutes to make
- You can adjust the sweetness and tang to your liking
- It’s fresher and brighter than the original, thanks to real grated onion
After making this every week for months, I can say confidently: this version is a staple in our house, and my family even prefers it to the store-bought kind!
Essential Ingredients
- Sweet Onion: A must for that mild, distinct flavor
- Two Vinegars: Red wine and white vinegar add tangy depth
- Sesame Oil: Just a touch brings rich, toasty undertones
- Fresh Spices: Paprika, garlic, onion powder, and more add complexity
- Cornstarch: Gives the sauce that perfect, clingy texture
Homemade Sweet Onion Sauce Recipe
Prep Time: 5 Minutes
Cook Time: 10 Minutes
Total Time: 15 Minutes
Yield: 8 Servings (about 2 cups)
Ingredients
Main Ingredients:
- 1 cup sugar
- 1/2 cup water
- 6 tablespoons white vinegar
- 1 1/2 tablespoons red wine vinegar
- 1/2 tablespoon freshly grated sweet onion
- 1 tablespoon cornstarch
- 2 teaspoons Dijon mustard
- 2 teaspoons mustard powder
Seasonings:
- 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
- Warm the Vinegars: Slightly warm the white and red wine vinegar before adding them to the mixture to help dissolve the sugar more effectively.
- Combine Ingredients: In a medium saucepan, whisk together all ingredients.
- Cook the Sauce: Bring the mixture to a gentle boil while whisking constantly. Let it boil for 5 minutes.
- Simmer: Reduce heat to low and simmer for another 5 minutes, continuing to whisk.
- Cool and Store: Remove from heat and allow to cool completely before transferring to an airtight container. Refrigerate for up to 1 week.
Tips for the Best Sauce
- Grate the Onion Finely: Use a microplane for nearly liquified onion.
- Prevent Lumps: Always mix cornstarch with cold water first.
- Let It Cool: Sauce thickens as it cools, so don’t judge the final consistency too early.
Troubleshooting
- Too Thick? Add a splash of warm water.
- Too Thin? Stir in a bit more cornstarch mixed with cold water.
- Lacking Tang? Add vinegar one teaspoon at a time until it pops.
Delicious Ways to Use It
Beyond Sandwiches:
- Brush on grilled chicken or salmon
- Toss with roasted vegetables or warm quinoa
- Drizzle over pizza or baked potatoes
- Mix into tuna, egg, or chicken salad
Snack & Party Ideas:
- Dip for onion rings or fries
- Mixed with cream cheese for a unique bagel spread
- Drizzled on grilled veggies or burger patties
- Added to coleslaw or mashed potatoes for extra flavor
Storage Tips
- Use a clean squeeze bottle for easy use
- Store in the coldest part of your fridge
- Let it sit out for 5 minutes before using if it thickens too much
Final Thoughts
This sauce has become more than a Subway copycat—it’s our go-to condiment. It’s endlessly customizable and incredibly versatile. Whether you’re slathering it on a sandwich or drizzling it over roasted vegetables, it adds a sweet-savory kick that lifts any dish. Try it once, and you’ll be hooked!