tablespoons fresh orange juice
tablespoon fresh lemon juice
teaspoons red-wine vinegar
tablespoons olive oil
lb large oyster mushrooms, stems trimmed
teaspoon coarse sea salt (preferably Sicilian)
Whisk together juices, vinegar, and oil in a large bowl. Toss mushrooms with vinaigrette and marinate 15 minutes. Transfer mushrooms to another bowl with tongs, reserving vinaigrette. Prepare grill for cooking. If using a charcoal grill, open vents on bottom of grill, then light charcoal. Charcoal fire is hot when you can hold your hand 5 inches above rack for 1 to 2 seconds. If using a gas grill, preheat burners on high, covered, 10 minutes, then reduce heat to moderately high. Grill mushrooms in 3 batches on oiled grill sheet set on grill rack, with grill covered only if using gas grill, turning frequently, until golden brown, about 5 minutes per batch. Transfer to vinaigrette as grilled, then toss with sea salt.