Easy Subway sweet onion sauce recipe made from scratch in about 15 minutes. If you love Subway’s sweet onion sauce, this copycat version is for you.
Subway is a well-known chain specializing in sandwiches and salads, and their sweet onion sauce is one of the most popular condiments on the menu. This sauce is a sweet, tangy, onion-forward dressing that’s perfect on subs or as a salad dressing.
The recipe below closely replicates the flavor and texture you get at Subway. It balances sweetness and tang, making it a great pairing for chicken teriyaki, turkey, tuna, or roasted vegetables. It’s quick, inexpensive, and easy to make at home when you’re craving a Subway-style sandwich.
This sweet onion sauce is:
- vegan
- gluten-free
- preservative-free
- oil-free
- kid-friendly
What to eat with Sweet Onion Sauce
Sweet onion sauce works wonderfully on tuna, chicken, or turkey subs, but it’s versatile beyond sandwiches:
Spread: Use as a spread on bread or wraps.
Salad dressing: Drizzle over greens for an instant flavor lift.
Dipping sauce: Serve with roasted, grilled, or fried vegetables, fish, or chicken.
Marinade: Use to marinate meats, chicken, or fish before cooking.
I also enjoy it with chips, french fries, baked potatoes, paratha, and pita. It complements many dishes and snacks.
Is this Sweet Onion Sauce Healthy
This homemade version is generally better than many store-bought alternatives in terms of fat and sodium. It does contain sugar, so consume it in moderation if you’re watching sugar intake.
Sweet Onion Sauce Ingredients
The ingredients are simple and fresh. Once prepared, the sauce comes together quickly. You will need:
Onion: any sweet variety such as Walla Walla, Texas Sweets, Maui, or Vidalia. Regular white or yellow onion also works.
Garlic: a small amount of fresh garlic to enhance flavor. Garlic powder can be substituted if needed.
Vinegar: a combination of white distilled vinegar and balsamic vinegar for depth and tang.
Granulated sugar: you can substitute brown sugar if preferred.
Cornflour/cornstarch: to thicken the sauce. Arrowroot, tapioca starch, or potato starch work as alternatives.
Black pepper: freshly ground for best flavor.
Nigella seeds (kalonji): optional; they add a subtle oregano/onion-like note. Skip if unavailable.
Lemon juice: fresh; adds brightness.
Salt: regular table salt, to taste.
Water: cold filtered water.
How to make Subway Copycat Sweet Onion Sauce
This sauce is straightforward and takes about 15 minutes from start to finish.
- Peel the onion and garlic, roughly chop, and blend until smooth. Strain the blended mixture through a muslin or fine sieve to extract the juice and transfer it to a pan or pot.
- Heat the pan, add the onion-garlic juice, water, sugar, salt, white vinegar, balsamic vinegar, black pepper, and nigella seeds. Bring the mixture to a boil and simmer until the sugar dissolves.
- Mix 1/4 cup water with the cornflour/cornstarch to form a slurry. Whisk the slurry into the simmering mixture and stir continuously over medium heat until the sauce thickens and becomes glossy.
- Remove from heat and stir in fresh lemon juice. Let the sauce cool to room temperature, then transfer to an airtight container and refrigerate.
How to store
Allow the sauce to cool completely, then store it in an airtight container in the refrigerator. It will stay fresh for about 5–7 days. Freezing is not recommended, as texture and flavor may change.
FAQ
Subway does not sell their proprietary sweet onion sauce separately. You can find similar sweet onion dressings from other brands at many grocery stores, but the closest match is to make this homemade copycat recipe.
If you try the recipe, please leave a comment and rating—feedback helps other readers and is appreciated.
Recipe
Subway Sweet Onion Sauce Recipe
Equipment
- Blender or grinder, measuring cups and spoons, pan or pot, spatula
Ingredients
- 1 medium-size onion
- 2 garlic cloves
- 3/4 cup water (plus 1/4 cup for slurry)
- 1/3 cup granulated sugar
- 1 teaspoon balsamic vinegar
- 1 teaspoon white vinegar
- 1/4 teaspoon nigella seeds/kalonji (optional)
- 1/4 teaspoon black pepper, freshly ground, or to taste
- 1/4 teaspoon salt, or to taste
- 2 teaspoons cornflour/cornstarch
- 1/2 teaspoon lemon juice, fresh
Instructions
- Peel the onion and garlic, roughly chop them, and blend until smooth. Strain the puree through a muslin cloth or fine sieve to extract the juice and transfer it to a pan or pot.
- Heat the pan and add the onion-garlic juice, water, sugar, salt, white vinegar, balsamic vinegar, black pepper, and nigella seeds. Bring to a boil and simmer until the sugar dissolves.
- Whisk 1/4 cup water with the cornflour/cornstarch to form a smooth slurry.
- Add the slurry to the simmering mixture and stir continuously over medium heat until the sauce thickens and becomes glossy.
- Remove from heat and stir in the fresh lemon juice. Allow the sauce to cool to room temperature.
- Transfer to an airtight container and refrigerate. Use as needed.
Notes
Be sure to taste and adjust seasoning as needed to avoid over-seasoning.
Ingredient notes:
Onion: Any sweet variety is best, though white or yellow onions will work.
Garlic: A small amount for flavor; garlic powder can be used if necessary.
Vinegar: A mix of white distilled and balsamic adds balance.
Sugar: Granulated or brown sugar both work.
Thickener: Cornflour/cornstarch works well; arrowroot, tapioca, or potato starch are alternatives.
Nigella: Optional, adds a subtle savory note if available.
Nutrition Disclaimer:
Nutrition information is an estimate. Actual values depend on ingredient brands and quantities used. Consult a nutrition calculator or registered dietitian for precise values.