Cut in half and toss with garlic, vinegar, olive oil, balsamic, lemon juice, and salt and pepper. Marinate at least 10 minutes or up to 1 hour, no longer.
Preheat grill to medium high heat.
Add mushrooms to the grill and cook 8-12 minutes turning occasionally.
Notes
Wipe mushrooms with a clean paper towel instead of rinsing with water.
Keep small mushrooms whole.
Marinate mushrooms for a minimum of 10 minutes, but no longer than an hour to keep them firm.
Refrigerate leftovers in a covered container for up to 3 days.