Don't be overwhelmed by the large ingredient list, this sweet onion sauce takes less than 15 minutes of work for a condiment that lasts almost forever. It's a great addition to anyone's sandwiches and it couldn't be easier to make. It's just a bonus that it doesn't have any funny preservatives.
This recipe is part of a series recreating all the best recipes from Subway. You can find this mega-post here.
Contents
Equipment Needed
Usually I have some recommendations on how to make my recipes easier with my favourite kitchen tools, but for this, all you really need is a pot (small in size is fine) and a whisk. For a bit of an easier time, a garlic press is recommended, but you can use a cheese grater for grated onion if you don't have a garlic press or juicer to extract onion juice.
The only hard part about this recipe is being able to wait for it to reach optimal flavour during the 6 hour rest time. It smells amazing when you're making it but trust me, you want to let it rest for the best taste.
Sweet Onion Sauce Ingredients
With a whopping 17 ingredients, this recipe may seem overwhelming, but there's only one ingredient found outside a spice cabinet or pantry. The less common ingredients like sesame oil and poppyseeds may not be in every household, but they last forever.
The only non-shelf stable ingredient is onion juice, which comes from taking an onion through a juicer (or preferably a garlic press) to get the flavour but not the texture. As mentioned above, you can grate the onion instead if you don't mind a slightly stronger and milled onion taste/texture.
Subway's Sweet Onion Sauce
Ingredients
- ⅔ cup sugar granulated
- ½ cup cold water
- 6 tbsp vinegar white or distilled
- 1 ½ tbsp red wine vinegar
- 1 tbsp cornstarch or arrowroot powder
- 1 tbsp minced onion flakes
- 2 ½ tsp dijon mustard
- 2 ½ tsp mustard powder
- ¾ tsp celery salt
- ¾ tsp fresh onion juice use a garlic press to juice
- 1 tsp poppyseeds
- ½ tsp onion powder
- ¼ tsp garlic powder
- ½ tsp salt
- ⅓ tsp paprika
- ¼ tsp black pepper
- 1 - 2 drops sesame oil
Instructions
- In a small pot, whisk together all ingredients over medium high heat - allow to bring to a boil while whisking constantly.
- Reduce heat to low and simmer, stirring until thickened - around 5 minutes.
- Allow to cool in the refrigerator overnight.
- This sauce keeps indefinitely if stored in a sealed jar in the fridge.
I LOVE their sweet onion sauce. So glad I now have the recipe to use at home!
Thank you so much, Beth! I hope you love it 🙂
Interesting to know what's in the Subway sweet onion sauce.
It's so easy to make! Hope you love it, Mai!
This looks so delicious and flavorful! I can’t wait to give this a try! My hubby is going to love this recipe!
Thank you Beth! I hope you and your husband love it <3!
This is great! We're always trying to replicate our beloved restaurant sauces and seasonings, so we'll definitely be trying this one out!
Thank you so much, Gita! I hope you love it
The sweet onion sauce was always my favorite part of a sub - I'm so excited to be able to make this at home now that there's no Subway near me! Yay!
I have up fast food this year so I totally relate Jenn! I hope you love it 🙂
Love how easy this recipe is. It’s perfect for our family!
Thank you so much Shadi! It’s amazing how easy it is.
My family is going to love this, thank you for the recipe!
This sounds delicious! It's so easy and everyone is going to love it!
Thank you so much, Danielle! Hope you love it
I don't mind all the ingredients because this is such a good sauce! Perfect for a juicy burger off the grill!
Thank you so much Whitney! I'm so glad you liked it 🙂
Does anyone know if there are any close copies to Subway's Sweet Onion Sauce that are available in your local grocery store?
Hi William! The closest I've tried is Renees Sweet Onion Vinaigrette, but I still prefer this version 🙂 If I'm feeling lazy it's an okay substitute though!