Get this all-star, easy-to-follow Grilled Portobello Burger with Onion Jam recipe from Food Network Kitchen Ingrédients Vegetarian Fruits et légumes 1 Garlic clove 1 Lettuce, leaves 4 Portobello mushrooms, large 3 Red onions, thinly sliced (about 2 pounds), medium large 2 sprigs Thyme, fresh Condiments 2 tbsp Balsamic vinegar 1/4 cup Honey 3 tbsp Horseradish, prepared Aides culinaires et épices 1 Kosher salt and freshly ground black pepper Huiles et vinaigres 4 tbsp Olive oil, extra-virgin 1/4 cup Red wine vinegar Pains et viennoiseries 4 Buns, whole grain Produits laitiers 2/3 cup Yogurt, low-fat plain Bières, vins et spiritueux 1 cup Red wine