Portobello Mushroom Burger

Instructions

1. Prepare the marinade
   In a small bowl, whisk together the balsamic vinegar, olive oil, minced garlic, dried thyme, salt, and pepper until well combined. Place the cleaned portobello mushroom caps in a large zip-top bag or shallow dish and pour the marinade over them. Gently toss to coat evenly. Marinate for at least 15 minutes, turning occasionally.
2. Preheat the grill
   Preheat your grill or grill pan to medium-high heat (about 400°F/200°C). Lightly oil the grates to prevent sticking. If using an oven, preheat to 375°F (190°C).
3. Grill the mushrooms
   Remove the mushrooms from the marinade, allowing excess liquid to drip off. Place the mushrooms on the grill, gill side up first, for about 5-6 minutes. Flip and cook for another 5-6 minutes until tender and juicy. If using cheese, place a slice on each mushroom during the last 2 minutes of cooking to melt. If using an oven, place mushrooms on a baking sheet and roast for 15 minutes, adding cheese for the last 3 minutes.
4. Prepare the toppings
   While the mushrooms are cooking, prepare your toppings. Slice the avocado, tomato, and red onion. Wash and dry the arugula or mixed greens. If using mayonnaise, spread it on the inside of the top buns.
5. Assemble the burgers
   Place the bottom half of each toasted bun on plates. Add a grilled portobello mushroom cap to each bun, followed by a slice of tomato, avocado slices, red onion rings, and a handful of arugula. Add the top bun and serve immediately while the mushrooms are still warm.
6. Serve and enjoy
   Serve the burgers immediately with your choice of sides such as sweet potato fries, a side salad, or coleslaw. These burgers pair well with a light beer, iced tea, or homemade lemonade.