• 1/2 tsp prepared yellow mustard
• 1/4 tsp freshly ground black pepper
• 1 Tbsp dark balsamic vinegar
• 1 Tbsp cornstarch dissolved in 1 tablespoon water
• 2 Tbsp cold unsalted butter

Instructions

1. Peel onions and cut in half. Thinly slice.
2. Melt the butter in a saucepan over medium high heat.
3. Add the sliced onions and sugar and cook for about 30min until caramelized.
4. Add the red wine and herbs, bring to a rapid boil for 2 minutes.
5. Reduce the heat and simmer for 10 minutes.
6. Add the stock, mustard, salt, pepper and Worcestershire sauce, bring to a boil.
7. Reduce the heat to a low simmer and simmer, covered, for 20 minutes.
8. Remove sprigs of herbs.
9. Add the vinegar, whisk in the cornstarch, and simmer another minute or two until thickened, whisking continuously.
10. Add the cold butter and whisk until dissolved.
11. Add salt and pepper to taste and more mustard if desired.

Notes:

Source: daringgourmet.com – Kimberly Killebrew