Cut the berries in half, reserving a few whole ones for garnish. Heat the oil ina saucepan; add the onion and saute over medium to medium-low heat for 7 minutes, or until soft and slightly browned. Add the garlic and cook briefly.
Add the vinegar and wine, simmering until almost dry. Add the beef broth, and simmer until almost dry. Stir in the halved beries, then remove from the heat.
Season to taste with salt, pepper, brown sugar and thyme. You want just enough sugar to balance the tartness of the berries. The residual heat from the pan and onions will soften the berries.
Garnish with the whole berries. Serve warm or at room temperature or refrigerate if not suing soon. Let come to room temperature before serving.