1. In a medium saucepan, combine sugar, red wine vinegar, white vinegar, grated onion, sesame oil, Dijon mustard, mustard powder, onion powder, garlic powder, paprika, celery seed, poppy seeds, salt, and pepper.

2. Whisk until smooth.

3. In a small bowl, mix cornstarch with a little water until smooth.

4. Add cornstarch mixture to saucepan and whisk until well combined.

5. Bring mixture to a boil over medium heat, stirring constantly.

6. Reduce heat to low and simmer for 5 minutes, or until sauce has thickened.

7. Remove from heat and let cool.

8. Use sauce as soon as it cools, or refrigerate for several hours to allow flavors to meld together.

Tips:

1. Use small holes on a cheese grater or a microplane to grate onion.

2. Add red pepper flakes or cayenne pepper for a spicy version.

3. Use sauce on sandwiches, salads, pizza, shredded or baked chicken, and vegetables.