In a large bowl, mix flour, sugar, yeast and salt.
Heat water to 120-130 degrees and add it to the flour mixture.
Mix to form into dough,
Knead on a floured surface and form into a ball.
Cover the dough and let it rise for an hour until it has doubled in size.
Return dough to a floured surface and divide into 8-10 equal portions.
Roll out each portion so it is fairly thin and 6-7 inches in diameter.
Cook dough on a hot grill for 2-3 minutes on each side. Turn flatbread over when the dough starts getting darker and appears cooked.
When the bread is cooked, remove from grill and spread on pesto. Cover with sliced mozzarella and sun dried tomatoes.
Return to grill and set heat to low. Shut the cover and leave the flatbread in for a few minutes until the cheese starts to melt.