Preheat the oven to 450°. In a large, heavy saucepan, heat the olive oil over medium-high heat. Add the onions, garlic, thyme and 1/2 teaspoon each salt and pepper, lower the heat to medium and cook, stirring, until the onions are golden, about 15 minutes. Stir in the wine and cook for 3 minutes. Add the beef broth, reduce the heat to low and cover the saucepan.