Marinated Portobello Mushroom Sandwich with Grilled Bell Pepper, Melted Gruyere cheese, and Mozzarella.

Roasted Portobello Mushrooms:

In a large mixing bowl, combine olive oil, salt/pepper to taste, garlic, balsamic vinegar, onion powder and thyme leaves.
Clean mushrooms and remove stems. Wipe them with a damp cloth.
Marinate the mushroom in an olive oil mixture for at least 15 minutes.
Preheat the oven to 400°.
Place the mushrooms on a baking sheet.
Roast for about 10-15 minutes or until tender.

Grilled Bell Pepper:

In a mixing bowl, mix together bell pepper, olive oil, balsamic, sea salt/black pepper, basil.
Place the bell pepper on a grill over medium heat and cook for about 8-10 minutes or until crisp tender and until the skin is completely charred.
Remove the bell pepper from the heat, when cooled, remove the charred skin. Cut into small pieces and remove seeds. Optional: add salt/pepper according to your liking.

To Assemble the sandwich:

Assemble the sandwich with a slice of bread, a slice of Gruyere cheese, chopped portobello mushrooms, grilled bell pepper, a slice of Mozzarella cheese and another slice of bread.
In a cast iron or non-stick skillet over medium low heat, heat 1 tablespoon salted butter.
Place the sourdough sandwich in a skillet, press slightly until golden, flip carefully, add more butter if needed, cook the other side until golden and the cheese melts for about 3-4 minutes.