Heat a nonstick skillet over medium-high heat. Coat pan with cooking spray. Add pancetta to pan; cook 3 minutes or until crisp. Drain on paper towels.
Cut lettuce head in half; cut each half into 2 wedges. Place 1 wedge on each of 4 salad plates. Drizzle each wedge with 2 tablespoons of Herbed Lemon-Buttermilk Dressing; sprinkle with 1/4 cup tomato and 2 tablespoons cucumber. Sprinkle evenly with pancetta. Serve immediately.