Prepare pasta according to package directions; drain.
Place bell peppers, mushrooms, and garlic cloves on a 24- x 12-inch piece of nonstick aluminum foil or lightly greased heavy-duty aluminum foil. Sprinkle bell pepper mixture with capers, cilantro leaves, and 1 tablespoon lemon juice. Fold aluminum foil to seal, leaving an opening in top for steam to escape.
Grill, covered with grill lid, over high heat (400° to 500°) 20 minutes or until peppers are almost blackened, and mushrooms are tender. Remove foil packet from grill. Seal foil, and let stand 10 minutes to loosen skin on peppers. Peel peppers, and discard skin.
Process roasted peppers, remaining items in aluminum foil packet, olive oil, next 3 ingredients, and remaining 1 tablespoon lemon juice in a food processor or blender until smooth, stopping to scrape down sides. Serve sauce over hot cooked pasta. Sprinkle with cheese, if desired.