Ingredients:

  • 4 large Portobello Mushroom Caps
  • 1 tablespoon (15 ml) Olive Oil (extra virgin)
  • ½ teaspoon (3 g) Kosher Salt
  • Pinch of freshly ground Black Pepper
  • 450 g (1 pound) Ribeye or Sirloin Steak, trimmed and very thinly sliced
  • 1 tablespoon (15 ml) Olive Oil (or neutral oil)
  • 2 tablespoons (30 g) Unsalted Butter
  • 1 large Yellow Onion, thinly sliced
  • 1 medium Green Bell Pepper (Capsicum), seeded and thinly sliced
  • 2 cloves Garlic, minced
  • 1 teaspoon (5 ml) Worcestershire Sauce
  • ½ teaspoon (3 g) Dried Oregano
  • 1 teaspoon (5 g) Kosher Salt
  • ½ teaspoon (2.5 g) freshly ground Black Pepper
  • 120 g (4 oz) Sliced Provolone Cheese, high-quality (or 4 slices)
  • 60 g (2 oz) Monterey Jack or Sharp Cheddar Cheese, grated (optional)

Instructions:

  1. Preheat your oven to 190°C (375°F). Line a baking sheet.
  2. Gently wipe the Portobello caps clean. Using a small spoon, carefully scrape out the dark gills from the underside of the mushrooms.
  3. Place the caps stem-side up on the prepared baking sheet. Drizzle with 1 tablespoon of olive oil, then season the inside cavity with salt and pepper.
  4. Bake the caps for 10 minutes (Par-Bake) to allow them to soften and release excess moisture. Remove from the oven and carefully blot any pooled liquid inside the caps with kitchen paper.
  5. Heat butter and 1 tablespoon oil in a large skillet over medium heat. Add the sliced onions and bell peppers. Cook, stirring occasionally, for 8–10 minutes, until tender and the onions are just starting to caramelise.
  6. Stir in the minced garlic and cook for 1 minute until fragrant. Remove the vegetable mixture from the pan and set aside in a bowl.
  7. Increase the heat of the skillet to medium-high or high. Add the thinly sliced steak to the hot pan (work in batches if necessary). Cook quickly for 1–2 minutes, stirring often, until the steak is just browned.
  8. Reduce the heat slightly. Stir in the Worcestershire sauce, dried oregano, and the remaining salt and pepper. Return the sautéed onion and pepper mixture to the pan. Toss everything together briefly to combine and heat through.
  9. Carefully spoon the cheesesteak mixture into the par-baked mushroom caps, pressing gently to create a generous mound.
  10. Place a slice of Provolone over the filling of each mushroom cap, then sprinkle with the grated Monterey Jack/Cheddar (if using). Return the stuffed mushrooms to the oven and bake for 5–8 minutes.
  11. Switch the oven to the high grill (broiler) setting. Cook for 1–2 minutes until the cheese is beautifully melted, bubbly, and slightly browned in spots. Serve immediately.