Combine chicken stock, peppercorns, parsley stems, and fennel seeds in a small sauce pot. Bring to boil. Reduce to a simmer. Cook until reduced by 1/2, about 20 minutes.

Heat enough oil to cover the bottom of a medium saucepan. Add red onion. Sweat over medium-low heat until onions begin to become translucent. Add worcestershire sauce. Reduce by 3/4.

Strain then add chicken stock and roasted garlic. Whisk. Bring to a boil for 2 minutes. Reduce to a simmer. Cook 5 minutes.

Whisk cornstarch and cold water. Add to sauce while whisking. Bring back to a boil for 30 seconds.

Reduce to a simmer. Add tarragon. Stir. Adjust seasoning. Serve.

Variations; Vegetable stock, vegetable oil, butter, capers, celery, celery seed, chervil, chives, lemon, grapefruit, mustard, mushrooms, orange, paprika, shallots, fines herbes, thyme, lovage, marjoram, mint, tomato, spinach, leeks, vinegar, sherry, red wine, apple juice or concentrate,