Caramelized Onion Mashed Potatoes with wine

3 large onions , peeled, halved and sliced in the food processor 2 tablespoons butter 2 tablespoons olive oil 6 garlic cloves , sliced 1 teaspoon pepper 1[...]

3 tablespoons butter 4 onions , cut in half and sliced 1/2-inch thick 1 tablespoon white wine vinegar 1/2 teaspoon ground thyme 6 large baking potatoes ,[...]