Description
This Mushroom Patty Melt recipe features roasted portobello mushrooms, caramelized onions, gooey Swiss cheese, and golden rye bread to create a comforting, flavorful meatless classic sandwich. Perfectly balanced with savory balsamic and soy glaze, it offers a satisfying vegetarian twist on the traditional patty melt.
Ingredients
Mushrooms and Marinade
- 4 large portobello mushrooms
- 2 garlic cloves, minced
- ¼ cup balsamic vinegar
- ⅛ cup soy sauce
- ½ tsp dried thyme
- ½ cup vegetable oil, divided
Caramelized Onions
- 1 colossal onion, sliced
Sandwich Assembly
- 8 slices rye bread
- ⅓ cup mayonnaise
- 8 slices Swiss cheese
- ¼ tsp salt
- 4 Tbsp butter, divided
Instructions
- Preheat and prepare ingredients: Preheat your oven to 400°F (200°C). Gather all ingredients and prepare them as follows to ensure a smooth cooking process.
- Caramelize the onions: Heat ¼ cup vegetable oil in a medium skillet over medium heat. Add sliced onions and cook, stirring occasionally, for about 45 minutes until they become caramelized and golden brown. Remove onions and set aside. Wipe out the skillet to prepare for toasting the sandwiches later.
- Prepare and roast the mushrooms: Clean the portobello mushrooms, removing stems and gills. Place mushroom caps cap-side down on a parchment-lined baking sheet. In a small bowl, whisk together minced garlic, balsamic vinegar, remaining ¼ cup vegetable oil, soy sauce, and dried thyme. Pour this marinade over the mushrooms, allowing some to overflow on the tray. Roast mushrooms in the preheated oven for 20 minutes. Remove and let cool, then slice.
- Assemble the patties: Lay out the rye bread slices and evenly spread mayonnaise over all eight slices. Top each slice with Swiss cheese and caramelized onions. Place sliced mushrooms onto four slices, sprinkle with salt, and then close sandwiches with the remaining bread slices, cheese side down to form four sandwiches.
- Toast the patty melts: Melt 1 Tbsp butter in the cleaned skillet over medium heat. Place two sandwiches in the skillet and toast for 3–4 minutes until golden brown. Add another tablespoon of butter, carefully flip the sandwiches, and cook for another 3–4 minutes on the other side. Repeat this process with the remaining two sandwiches and butter. Serve immediately and enjoy the warm melty goodness.
Notes
- You can substitute Swiss cheese with provolone or mozzarella for a milder flavor.
- Caramelizing onions is time-consuming but adds deep flavor; using a slow, low-heat method is important.
- If a skillet isn’t available, you can finish the sandwiches under a broiler, flipping halfway to melt cheese evenly.
- For vegan variation, use vegan mayo, plant-based cheese, and olive oil or a vegan butter substitute.
- Leftover mushrooms and onions can be stored in the refrigerator for up to 3 days.
