2 ounces (about 1/2 cup ) thinly sliced prosciutto, cut in bite-size pieces
Start charcoal fire or preheat gas grill to medium-high heat.
Combine 1 cup flour, undissolved yeast, sugar and salt in a large bowl. Add very warm water and oil; mix until well blended, about 1 minute. Gradually add enough remaining flour to make a soft dough. Dough should form a ball and will be slightly sticky. Knead** on a floured surface, adding additional flour if necessary, until smooth and elastic, about 4 minutes. (If not using Pizza Yeast, let dough rest 10 minutes.)
Divide dough into 4 portions. Pat or roll dough on a well-floured counter to about 6 to 8-inch circles; they do not need to be perfect.
Using hands, lift each crust carefully and place on well-oiled grill. Cook for 3 to 4 minutes until bottom is lightly browned and top looks set. Using long handled tongs, remove crust from grill, grilled side up, to a platter or baking sheet.
Brush with approximately 1 tablespoon of basil pesto per crust. Divide remaining topping ingredients evenly between the crusts.
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 grill and 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.