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.
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
- 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
- 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.