Simple Sweet Onion Sauce (Subway Copycat) (2024)

This sweet onion sauce is quick, easy, and made with minimal ingredients. It’s just what your sandwiches, homemade subs, and salads have been needing! Try this Subway copycat for a slightly tangy, sweet, and preservative-free option when the need arises.

Why you’ll love this recipe

• Easy: Whisk, blend, and strain — that’s all there is to it for this easy recipe.
• Affordable: Using affordable everyday ingredients, this is a sauce you can make over and over again.
• Versatile: Use Subway sweet onion sauce on salads, sandwiches, wraps, and more. The options are endless!
• Customizable: Make it sugar-free, creamy, spicy, or extra herbaceous. It’s extremely easy to customize this sauce.

What is sweet onion sauce?

If you’ve ever tried Subway’s infamous sweet onion sauce and couldn’t get enough, I have got a surprise for you! This homemade version tastes just like the original, but it can be made in the comfort of your own home. Plus, it doesn’t contain any hard-to-pronounce additives!

This simple dressing is made with just 6 ingredients, and it highlights a perfect balance between sweet and tangy. While a homemade sub is the most obvious choice to serve it on, this all-purpose sauce is great on all types of salads, from garden to quinoa!

Is sweet onion sauce vegan?

Much like the original, this sweet onion sauce is vegan-friendly since it contains no animal-derived products. If you’re more strict on how your ingredients are processed, ensure you’re using organic vegan sugar that’s not processed with bone char.

Ingredients & Substitutions

• Onion: Use white or yellow onions, although I prefer white onions for their crisp, clean flavor. If you can get your hands on some, I also recommend sweet onion varieties like Vidalia and Walla Walla.
• Water: To thin the sauce and mix with the potato starch.
• Sugar: Adds sweetness, balancing and enhancing the natural sweetness of the onions. Use cane sugar or vegan granulated sugar.
• White wine vinegar: I prefer the slightly sweeter, milder, and more delicate taste of white wine vinegar over regular white vinegar. It results in a well-rounded sauce rather than one overpowered by acidity.
• Poppyseeds: Just like Subway’s sweet onion sauce, don’t forget to include poppyseeds!
• Salt & pepper: Brings out the flavor of the sauce while adding a little kick!
• Potato starch: To thicken the sauce. If you don’t have potato starch, cornstarch is a great substitute.

Instructions

• Step 1: To make the slurry, whisk together the potato starch and water in a small bowl.

• Step 2: Roughly chop the onions and toss them into a blender with water. Mix them on high until they’re smooth (like onion juice).

• Step 3: Strain the onion juice through a fine-mesh sieve into a saucepan, using a spoon to slowly push the liquid through. It mostly all goes through the mesh sieve.

• Step 4: Heat the saucepan of onion juice over low-medium, then add the slurry and the remaining ingredients to thicken the sauce.

• Step 5: Bring the sauce to a quick boil, then immediately turn off the heat and let it cool. This sweet onion sauce will thicken more as it continues to cool.

How to use Subway sweet onion sauce

Once your onion sauce is cooled and thickened, use it in some of the following ways:

• Drizzled on sandwiches, subs, and paninis
• Served in wraps and pitas
• As a dip for pizza
• Used as a salad dressing
• Tossed with roasted vegetables

Storage

If you have leftover sauce, you’re in luck! It can be stored for quite a long time by following these storage instructions:

• Fridge: As long as it’s kept in an airtight container (I prefer a mason jar), this dressing will stay fresh for up to a month in the fridge.
• Freezer: This sauce is freezer-friendly, and the storage time can be extended up to 3 months. Just keep it in a freezer-safe container or jar.
• Thaw: When you’re ready to use it again, thaw the sauce in the fridge overnight. Don’t forget to give it a stir in the morning, especially if it’s separated.

Variations

• Sugar-free: Swap the sugar for stevia for a keto, diabetic, and sugar-free version.
• Creamy: For a creamier version, try adding 1-2 tablespoons of my vegan Kewpie mayo.
• Spicy: Add a slight kick with a teaspoon of Sriracha or sambal oelek.

Top tips

• Strain the onions: For the smoothest sweet onion sauce, blend and strain the onions into the saucepan.
• Simmer the sauce: To bring the flavors together and thicken the sauce, don’t skip simmering it.
• Make a slurry: To prevent the potato starch from clumping in the sauce, combine it with a small amount of water before adding it in.

FAQ

Similar Recipes

If you enjoyed this recipe, be sure to check out some more of my most popular sauces like these:

• Southwest Salad Dressing: A creamy, spicy, and tangy sauce made in 5 minutes.
• Vegan Caesar Dressing: Simple Caesar dressing made with plant-based ingredients.
• Sriracha Aioli: A rich vegan aioli with a spicy element!
• Maple Dijon Vinaigrette: Healthy dressing made with pantry staples.
• Caramelized Onions: If you love onions, try these sweet caramelized onions made without any sugar.