1 pound uncooked shrimp (26-30 per pound), peeled and deveined
1 medium red onion, cut into thick wedges
1 medium zucchini, cut into 1/2-inch pieces
1 medium yellow summer squash, cut into 1/2-inch pieces
8 cherry tomatoes
Place first 8 ingredients in a food processor; process until pureed. Reserve 6 tablespoons mixture for serving. Place remaining mixture in a bowl; toss with shrimp and vegetables. Let stand 15 minutes.
Alternately thread shrimp and vegetables onto 8 metal or soaked wooden skewers. Grill, covered, over medium heat or broil 4 in. from heat until shrimp turn pink, 3-4 minutes per side. Serve on bed of additional herbs with crusty bread and reserved sauce.