Leftover Prime Rib Beef Stroganoff

Start with a large, deep frying pan or dutch oven. Heat the olive oil to medium high heat, then add minced shallot and garlic and cook for 1 minute (just enough to start sweating the shallot). Add butter and melt with the shallot and garlic.
Add the all-purpose flour, and combine with shallot and garlic until all of the flour is absorbed. Add seasoning (tarragon, ground sage, thyme, salt & pepper) and mushrooms. Stir to combine, then add the beef broth, Worcestershire, and Dijon.
Stir all of the gravy ingredients, reduce heat to medium and allow to simmer (reducing heat as necessary to maintain a low simmer) for about 10 minutes. Gravy should thicken while simmering.
Once gravy has simmered and reduced, slightly thickening, add the sliced leftover prime rib roast meat and cook an additional 2-3 minutes to heat the meat through completely. Remove from heat and add sour cream. Serve immediately over cooked pasta, rice, or potatoes. Top with chopped parsley for garnish, if desired.