Grilled Portabella and Bulgur Salad "Sandwiches"

Ingredients

• 1 small firm-ripe avocado 
• 4 cups baby arugula 
• 1 cup bulgur 
• 1 pint cherry tomatoes 
• 0.5 cup flat-leaf parsley leaves 
• 1 large garlic clove 
• 1.5 tablespoons olive oil extra-virgin
• 0.3 cup pinenuts toasted
• 8 large portabella mushrooms for another use (see cooks' note, below
• 1 small onion red cut lengthwise into 1/2-inch-thick wedges (keeping root end intact)
• 0.3 teaspoon red-pepper flakes hot
• 0.3 cup red-wine vinegar 
• 1 tablespoon rosemary finely chopped
• 1.5 cups boiling-hot water 
• 2 medium bell peppers yellow quartered
• 1 medium zucchini halved lengthwise

Equipment

• food processor
• bowl
• knife
• sieve
• grill
• grill pan
• glass baking pan

Directions

1. With motor running, drop garlic into food processor and finely chop.
2. Add tomatoes, parsley, oil, vinegar, rosemary, red-pepper flakes, 1/2 teaspoon salt, and 1/4 teaspoon pepper and pulse until tomatoes are finely chopped but not puréed.
3. Peel skin from portabellas using tip of a paring knife, pulling from edge of mushroom toward center. Gently scrape off gills from mushrooms with tip of a spoon. Toss portabellas with 1/2 cup vinaigrette in a 13- by 9-inch glass baking dish and let stand, turning occasionally, 20 minutes.
4. Prepare a gas grill for direct-heat cooking over medium heat; see Grilling Procedure.
5. Push 1 wooden pick into each onion wedge to secure for grilling. Toss onion wedges, bell peppers, and zucchini with oil, 1/4 teaspoon salt, and 1/8 teaspoon pepper. Oil grill rack, then grill vegetables, covered, turning occasionally, until tender (6 to 8 minutes for bell peppers, 6 to 10 minutes for zucchini, 8 to 12 minutes for onion, and 12 to 15 minutes for portabellas).
6. Transfer portabellas to a plate and remaining vegetables to a bowl as cooked. Cool slightly, then remove wooden picks and coarsely chop onion, bell peppers, and zucchini.
7. While vegetables cook, pour boiling-hot water over bulgur with 1/2 teaspoon salt in a large bowl and let stand until water is absorbed and bulgur is tender, about 5 minutes.
8. Drain in a sieve if any water remains.
9. Add vegetables to bulgur with pine nuts and remaining vinaigrette and toss.
10. Put one fourth of arugula on each of 4 plates. Top with upside-down portabella. Pack bulgur mixture into a cup measure, then unmold on top of portabella. Top with another portabella, right side up.
11. Serve with an avocado quarter.
12. Vegetables can be grilled in an oiled hot 2-burner grill pan.