The Portobello & Beef Patty Melt is a delicious twist on the classic patty melt. This recipe combines juicy beef patties with sautéed portobello mushrooms and caramelized onions, all sandwiched between slices of toasted rye bread and melted Swiss cheese. The earthy flavor of the mushrooms complements the savory beef, while the melted cheese adds a creamy richness. This hearty and flavorful sandwich is perfect for a satisfying lunch or dinner.