Preheat the oven to 350°F. Season the short ribs with salt and pepper, then heat olive oil in a Dutch oven and sear the ribs on all sides, about 2–3 minutes per side. Transfer to a plate.
Lower heat to medium, add butter and onions. Sauté, stirring frequently, until the onions turn deep golden brown, about 20 minutes. Add tomato paste, garlic, thyme sprigs, and bay leaves, cooking 1 minute more.
Pour in red wine, bring to a simmer, and reduce by half, about 5 minutes. Stir in beef broth, Worcestershire sauce, balsamic vinegar, and sugar. Season lightly with salt and pepper.
Nestle the seared ribs back into the pot, cover, and transfer to the oven. Braise until the meat is tender, about 3–3½ hours. Remove, skim fat, and discard herbs.
Crostini
Arrange baguette slices on a baking sheet, top with shredded Gruyère, and broil for 1–2 minutes until the cheese is melted and bubbly.
Notes
Make sure to skim excess fat before serving to keep the sauce from being greasy.When reheating, add a splash of broth to loosen the sauce.Leftovers improve in flavor overnight.
Nutrition
Serving: 400gCalories: 650kcalCarbohydrates: 15g
Keyword braised beef, caramelized onions, French Onion Short Ribs, Gruyère, short ribs