If you’ve ever wished you could bottle up that signature tangy-sweet flavor from your favorite sandwich shop, you’re in luck with this Subway Sweet Onion Sauce! This homemade version is easy to whip up in just minutes, bringing the crave-worthy taste right into your own kitchen. The sauce is lusciously smooth, bursting with oniony zing and a playful pop of sweetness that transforms anything from sandwiches and salads to grilled meats. Once you realize how effortless and versatile it is, you’ll want to keep a jar of Subway Sweet Onion Sauce in the fridge at all times—trust me, it’s a total game-changer!
Ingredients You’ll Need
Let’s talk about what makes this sauce so special! Each ingredient plays a unique role in building those memorable layers of taste and texture you love. Using simple, pantry-friendly items, you’ll capture all the color, zest, and irresistible sweet-savory depth in every spoonful.
- White sugar: This is the base of our sweetness, giving the sauce its signature bold, shiny finish and flavor.
- White vinegar: The key to that bright, punchy tang—don’t skip it for a truly authentic taste.
- Cornstarch: Just a touch thickens the sauce to that drizzle-perfect consistency that clings to every bite.
- Water: Simple, but essential for dissolving and blending the thickener without clumping.
- Soy sauce: This brings a subtle umami richness, deepening the flavor without overpowering.
- Finely minced white onion: For best results, mince as finely as you can for maximum flavor and smoothness.
- Poppy seeds: Not just for looks—the tiny seeds add a fun burst and lovely texture to the final sauce.
- Dry mustard powder: This adds a little warmth and zing, balancing the sweetness.
- Salt: A small amount enhances all the other flavors without making the sauce overly salty.
- Garlic powder: Rounds everything out with just enough mellow savoriness.
How to Make Subway Sweet Onion Sauce
Step 1: Dissolve Sugar and Vinegar
Start by setting a small saucepan over medium heat. Pour in the white sugar and white vinegar, and stir gently as they warm up. Keep stirring until the sugar grains disappear completely and the mixture looks clear—this is your foundation for the perfect tangy-sweet base.
Step 2: Mix the Cornstarch Slurry
In a separate tiny bowl, whisk the cornstarch and water together until super smooth. No lumps allowed! This quick step ensures your Subway Sweet Onion Sauce thickens evenly and turns out silky instead of grainy.
Step 3: Combine Ingredients
Add your cornstarch mixture to the saucepan, then immediately stir in the soy sauce, finely minced onion, poppy seeds, dry mustard powder, salt, and garlic powder. The aroma right now is already a little magical.
Step 4: Simmer and Thicken
Bring your concoction to a gentle boil, then lower the heat. Stir frequently—after 2 to 3 minutes, you’ll notice the sauce thickening to a gorgeous syrupy consistency. Don’t walk away during this part; you want it glossy and just pourable, not sticky or clumpy.
Step 5: Cool and Store
Remove your saucepan from the heat and let the Subway Sweet Onion Sauce cool for a bit. Once it’s no longer hot, pour it into a clean jar or airtight container. Refrigerate until ready to use—this lets the flavors blend and intensify beautifully.
How to Serve Subway Sweet Onion Sauce
Garnishes
A sprinkle of fresh herbs—think parsley or chives—can be a lovely finishing touch. If you like things a bit spicy, a dash of red pepper flakes can add a subtle kick to the sweetness. For extra wow-factor, those extra poppy seeds on top really make your dish look special and echo the speckled look of the original sauce.
Side Dishes
The sweet and zesty flavor profile of this sauce plays brilliantly with grilled chicken, roasted veggies, or crispy tofu. Try serving it alongside crispy fries, potato wedges, or even a fresh slaw for a picnic-style feast. Of course, it’s right at home drizzled over subs, wraps, or hearty grain bowls—anything that benefits from a bright, sweet lift.
Creative Ways to Present
Dress up your Subway Sweet Onion Sauce by serving it in a cute little pourer or ramekin on a charcuterie board, for easy dipping. For parties, try swirling it over a platter of chicken skewers or veggie wraps for a snazzy look. Or, toss it with roasted chickpeas or drizzle over a colorful salad for a healthy, homemade “fast food” feel that everyone will love.
Make Ahead and Storage
Storing Leftovers
Keep any leftover Subway Sweet Onion Sauce in an airtight jar or container in the fridge. It stays fresh and full of flavor for up to two weeks, making it perfect for meal prep or those spontaneous sandwich cravings!
Freezing
If you want to save some for even longer, Subway Sweet Onion Sauce freezes well! Just pour into a freezer-friendly container, leaving a little space at the top. Thaw in the refrigerator overnight before using and give it a good stir to liven it back up.
Reheating
There’s usually no need to reheat this sauce, as it’s delicious cold or at room temp. But if you prefer it warmed, pop a little in the microwave for 10-15 seconds or gently warm on the stove. If it’s thickened in the fridge, just add a splash of water and stir until smooth.
FAQs
Can I make Subway Sweet Onion Sauce gluten-free?
Absolutely! Be sure to use a certified gluten-free soy sauce or tamari. All the other ingredients are naturally gluten-free, so you get all the flavor, minus the gluten.
How close does this taste to the real thing?
This homemade recipe is shockingly close to the original Subway Sweet Onion Sauce—sweet, tangy, and delightfully oniony. With just a few simple pantry ingredients, you can enjoy the same delicious drizzle at home!
Can I reduce the sugar for a lighter version?
You can experiment with reducing the sugar a bit if you like things less sweet, but it may slightly affect the texture and that signature flavor. I recommend making it as written the first time, then adjusting to suit your personal taste next batch.
Is this sauce vegan?
Yes, every ingredient in this recipe is plant-based, making Subway Sweet Onion Sauce a fantastic vegan condiment! It’s perfect for adding flavor to sandwiches, wraps, and grain bowls of all kinds.
What’s the best way to use Subway Sweet Onion Sauce?
This is the fun part—drizzle it over salads, use it as a dip, brush it onto grilled meats or tofu, or jazz up your homemade wraps and subs. Once you see how versatile it is, you’ll want to put it on practically everything!
Final Thoughts
Give this Subway Sweet Onion Sauce recipe a try, and you’ll have one of the most beloved sandwich shop flavors bottled up in your fridge. It’s ridiculously easy to make, completely customizable, and sure to bring a smile to every meal. Don’t be surprised when you find yourself reaching for it over and over—happy drizzling!
Print
Subway Sweet Onion Sauce Recipe
- Total Time: 10 minutes
- Yield: 1 cup 1x
- Diet: Vegan, Gluten-Free
Description
Learn how to make your own Subway-inspired sweet onion sauce at home with this easy recipe. This versatile sauce is perfect for adding a touch of sweetness and flavor to your favorite sandwiches, salads, and wraps.
Ingredients
Sauce:
- ½ cup white sugar
- ½ cup white vinegar
- 1 tablespoon cornstarch
- 1 tablespoon water
- 1 tablespoon soy sauce
- 1 tablespoon finely minced white onion
- 1 teaspoon poppy seeds
- 1 teaspoon dry mustard powder
- ½ teaspoon salt
- ¼ teaspoon garlic powder
Instructions
- Combine sugar and vinegar: In a small saucepan over medium heat, combine the sugar and vinegar, stirring until the sugar dissolves.
- Prepare cornstarch mixture: In a separate small bowl, whisk the cornstarch and water together until smooth, then add it to the saucepan.
- Add remaining ingredients: Stir in soy sauce, minced onion, poppy seeds, mustard powder, salt, and garlic powder.
- Simmer: Bring the mixture to a gentle boil, then reduce the heat to low. Simmer for 2–3 minutes, stirring frequently, until the sauce thickens.
- Cool and store: Remove from heat and let cool. Transfer to a jar or airtight container and refrigerate until ready to use.
Notes
- This sauce pairs perfectly with grilled chicken, deli sandwiches, wraps, or salads.
- For a thinner consistency, add a splash of water after cooling.
- Keeps in the fridge for up to 2 weeks.
- Prep Time: 5 minutes
- Cook Time: 5 minutes
- Category: Sauce
- Method: Stovetop
- Cuisine: American
Nutrition
- Serving Size: 1 tablespoon
- Calories: 35
- Sugar: 7g
- Sodium: 110mg
- Fat: 0g
- Saturated Fat: 0g
- Unsaturated Fat: 0g
- Trans Fat: 0g
- Carbohydrates: 8g
- Fiber: 0g
- Protein: 0g
- Cholesterol: 0mg
