Heat a small amount of olive oil and add the minced shallots.
Stir in the garlic and cook for 30 seconds more.
Add the tomato paste after that.
Pour in the red wine, scraping the bottom of the pan to loosen any browned bits. Simmer for 2–3 minutes.
Add beef stock, Worcestershire sauce, balsamic vinegar, Dijon mustard, and sugar.
Turn off the heat and stir in the cold butter until melted, making the sauce glossy.
Taste and adjust salt, pepper, or vinegar as needed.