Warm 4 tablespoons olive oil in a medium skillet over medium-high heat. Add the garlic cloves, pressing lightly on all sides to release the flavor until golden. Remove and discard. Add the onion and cook, stirring often, until translucent, about 3 minutes. Add the bread-herb mixture, peppercorns, cloves, and bay leaves, and cook over medium heat for 5 minutes, stirring often to blend flavors. Add the vinegar, cook for one minute, remove from heat and let cool.