Carefully slide each pizza onto the grill. Cook an additional 3 to 4 minutes until bottom of crust is browned and cheese is melted. Remove from oven and sprinkle with lettuce. Serve immediately.
*If you don't have a thermometer, water should feel very warm to the touch.
**To knead the dough, add just enough flour to the dough and your hands to keep the dough from sticking. Flatten dough and fold it toward you. Using the heels of your hands, push the dough away with a rolling motion. Rotate dough a quarter turn and repeat the "fold, push and turn" steps. Keep kneading dough until it is smooth and elastic. Use a little more flour if dough becomes too sticky, always working the flour into the ball of dough.
Make Ahead: Dough (but NOT individual crusts) may be made up to 24 hours in advance and stored covered in the refrigerator. Punch down and roll out just before grilling. OR, pizzas may be partially grilled ahead of serving. Here's how: Grill one side of the pizza crust. Cool. Tightly wrap and refrigerate until serving time. Top pizzas with desired toppings (on grilled side) and finish grilling on preheated grill.
Dough sticking to grill? Make sure grill has been preheated and cleaned. To prevent sticking, drizzle oil over paper towel and carefully wipe over grates. Or lightly brush pizza crusts on both sides with oil before grilling.