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A stacked grilled Mushroom Patty Melt filled with melted cheese, sautéed mushrooms, onions, and ground meat on toasted bread.

Mushroom Patty Melt

A comforting meatless sandwich with roasted portobellos, caramelized onions, and melted Swiss on golden rye bread.
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Prep Time 15 minutes
Cook Time 1 hour
Total Time 1 hour 15 minutes
Servings: 4
Course: Main Course, Sandwich
Cuisine: American, Vegetarian
Calories: 550
Ingredients Method Nutrition Notes

Ingredients
  

  • ½ cup Vegetable Oil divided for onions and mushrooms
  • 1 Colossal Onion thinly sliced, ~565 g, about 3 cups
  • 4 Large Portobello Mushrooms stems removed, caps cleaned
  • 2 Garlic Cloves minced, ~1 Tbsp
  • ¼ cup Balsamic Vinegar for mushrooms
  • ⅛ cup Soy Sauce low-sodium preferred
  • ½ teaspoon Dried Thyme
  • 8 Slices Rye Bread for sandwiches
  • ⅓ cup Mayonnaise or vegan mayo
  • 8 Slices Swiss Cheese or plant-based alternative
  • ¼ teaspoon Salt to season mushrooms
  • 4 tablespoon Butter divided, for toasting sandwiches

Method
 

  1. Preheat the oven to 400°F (200°C) and gather all ingredients.
  2. In a medium skillet over medium heat, warm ¼ cup vegetable oil. Add the sliced onions and cook, stirring occasionally, for about 45 minutes until golden and caramelized. Remove and set aside, then wipe out the skillet.
  3. Remove the stems and gills from mushrooms and place caps, cap side down, on a parchment-lined baking sheet.
  4. In a small bowl, whisk together garlic, balsamic vinegar, remaining ¼ cup vegetable oil, soy sauce, and thyme. Pour over mushroom caps and roast in the oven for 20 minutes. Allow to cool slightly, then slice.
  5. Spread mayonnaise evenly over all 8 slices of rye bread.
  6. Top each slice with Swiss cheese and caramelized onions. Add sliced mushrooms to 4 slices, sprinkle with salt, then close sandwiches with the remaining bread slices.
  7. Melt 1 tablespoon butter in the skillet over medium heat. Toast two sandwiches for 3–4 minutes, add another 1 tablespoon butter, flip carefully, and cook 3–4 more minutes. Repeat with the remaining sandwiches.
  8. Serve immediately and enjoy.

Nutrition

Serving: 1 ServingCalories: 550kcalCarbohydrates: 45gProtein: 18gFat: 33gSaturated Fat: 12gPolyunsaturated Fat: 4gMonounsaturated Fat: 15gCholesterol: 40mgSodium: 820mgPotassium: 500mgFiber: 4gSugar: 6gVitamin A: 350IUVitamin C: 8mgCalcium: 200mgIron: 3mg

Notes

For vegan options, swap mayonnaise and Swiss cheese with plant-based alternatives, and use oil for toasting the bread. Rich, melty, and full of umami flavor!

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