This is honestly the first time I have ever had a grilled portobello burger and I am hooked. I didn't miss the meat at all, and trust me...I'm a meat girl. I was originally going to try a balsamic marinade but I was craving something spicy and smoky so I switched to a chipotle marinade. And I'm so happy that I did. Even my husband liked it and he's more of a meat and potatoes kind of guy. We topped the burgers with pepper jack cheese and leftover marinade, and oh yeah, we used homemade hamburger buns (an extra bonus). I think avocado would also be a great addition, especially if you want to tone down the spice, but I didn't have any on hand. I highly recommend these if you are in to the spicy, smoky thing and are looking for something different.
Grilled Chipotle Portobello Burgers
4 large portobello mushroom caps, stems removed
1/3 cup vegetable oil
2 tbsp. fresh lime juice
3 chipotle peppers in adobo, chopped
2 garlic cloves, chopped
1/2 tsp. Mexican-style chili powder (or regular)
Toppings of choice (pepper jack cheese, avocado, grilled onions, etc)
Hamburger buns, lightly toasted
Gently clean the mushrooms using a damp paper towel or kitchen towel. In a small bowl, combine the next five ingredients for the marinade. Place the mushrooms in a 9 x 13 glass dish and pour the marinade over the mushrooms. Brush the marinade on both sides to coat. (The marinade lightly coats and may not completely cover both sides. This is still enough to sufficiently flavor the mushrooms.) Marinate for an hour at room temperature, turning once.
Preheat the grill over med-high heat. Place the mushrooms on the grill and cook for 4-6 minutes per side, turning once. Remove the mushrooms from the heat and top with any leftover marinade. Serve on a lightly toasted hamburger bun with toppings of choice.
Source: A Much Kneaded original