Make a batch of Baked Italian Meatballs. Exclude the 2 tablespoons of Italian Seasoning if you'd like.
Combine the red wine, shallots, black pepper, thyme, and bay leaf in a sauce pan. Bring to a boil and cook until reduce by half. Add beef stock and simmer for 15 minutes.
Mix together the corn starch and water.
Add the sherry and cornstarch mixture. Simmer until nice and thick. The sauce should coat the back of a spoon. If it doesn't, it needs to cook a little bit longer. Stir in the bone marrow, or butter. Heat until melted.
If using bone marrow there may be no reason to thicken with cornstarch. The collagen in the marrow will thicken the sauce.
Strain the sauce through a fine chinois.
For the crispy shallots: Heat 1 tablespoon oil in a fry pan. Slice the shallots into rounds and coat them with cornstarch. Fry over medium high heat until shallots are turning crispy and browned.
Yield 1 cup
Marrow added to sauces should be cooked just long enough to heat it through. Any longer and it will melt away to nothing.