Subway Sweet Onion Sauce (Copycat)

My reverse-engineered recipe for Subway's Sweet Onion Sauce, as requested by another Food.com member. It's quite sweet, but very tasty, if you've never tried it before.

• Ready In: 13 mins
• Serves: 16
• Yields: 1 cup

Ingredients

• 1  cup granulated sugar (plus 2 tablespoons)
• 1⁄2 cup  plus 1 tablespoon cold water
• 6  tablespoons white vinegar
• 1 1⁄2 tablespoons red wine vinegar
• 1  tablespoon arrowroot
• 1  tablespoon  minced  onion flakes
• 2 1⁄2 teaspoons Dijon mustard
• 2 1⁄2 teaspoons mustard powder
• 3⁄4 teaspoon  celery salt
• 3⁄4 teaspoon  fresh  onion juice (use a garlic press)
• 3⁄4 teaspoon poppy seed
• 1⁄2 teaspoon  onion salt
• 1⁄4 teaspoon  garlic salt (plus 1/8 teaspoon)
• 1⁄4 teaspoon paprika (plus 1/8 teaspoon)
• 1⁄4 teaspoon black pepper (plus 1/8 teaspoon)
• 1 -2  drop  sesame oil

Directions

1. WHISK sauce ingredients together in a small saucepan (1 cup plus 2 tablespoons granulated sugar, 1/2 cup plus 1 tablespoon cold water, 6 tablespoons white vinegar, 1 1/2 tablespoons red wine vinegar, 1 tablespoon arrowroot powder, 1 tablespoon minced onion flakes, 2 1/2 teaspoons Dijon mustard, 2 1/2 teaspoons mustard powder, 3/4 teaspoon celery salt, 3/4 teaspoon fresh onion juice, 3/4 teaspoon poppy seeds, 1/2 teaspoon onion salt, 3/8 teaspoon garlic salt, 3/8 teaspoon paprika, 3/8 teaspoon black pepper, 1-2 drops sesame oil).
2. BRING mixture to a boiling while whisking constantly.
3. REDUCE heat to low simmer, stirring until thickened and flavorful, about 5 minutes.
4. ALLOW to cool, then refrigerate in a sealed container (keeps indefinitely).
5. SERVE as a dressing for sandwiches or salads and enjoy!