In the bowl of a stand mixer fitted with a dough hook, combine the water, yeast, and sugar and mix for about 20 seconds. Let stand for 3 to 5 minutes to let the yeast dissolve.
With the mixer set at low speed, add 2 cups of the flour, the kosher salt, and 1 tablespoon of the olive oil and mix to blend. Add 2 more cups flour and mix to blend. Add the remaining flour and mix again.
Knead at medium speed for 7 to 8 minutes, until the dough is soft and pliable. The dough should be slightly tacky, but if it is extremely sticky you can add the additional tablespoon or two of flour (if it is a humid day you will very likely need this).
Detach the bowl from the mixer, roll the dough into a large ball, and return to the bowl. Cover with plastic wrap and let stand in a warm spot for 1½ to 2 hours, until it has doubled in size.
Divide the dough into 8 pieces and shape into rounds. Spray 4 rimmed baking sheets with nonstick olive oil spray or spoon 1 tablespoon of oil onto each sheet and tilt gently to spread it around. (If you don’t have 4 baking sheets, oil enough flat surfaces, such as platters or trays, to hold all 8.) Place the rounds on the sheets, at least 2 inches apart, and cover with plastic wrap. Let rest for 15 minutes.
Heat one side of the grill to high and the other side to low. (If your grill has a temperature control, the hot side should be between 450° and 500°F; the cool side should be between 325° and 350°F.)
When the dough has rested for 15 minutes, on a work surface, roll each round into a an 8-inch round flatbread shape, lightly salt on both sides (you will use about half of the Maldon salt for all 8). Place the salted flatbreads back on the oiled sheets.
When the grill is very hot, place the breads directly on the hot side of the grill, oil side down, for 90 seconds to 2½ minutes, or until it develops grill marks; then flip over and cook for 90 seconds to 2½ minutes longer. Move the flatbreads to the cooler part of the grill and cover the grill, allowing them to cook for 1 to 2 minutes. Work in batches if needed.
Transfer the grilled flatbreads to a clean platter, and, with a pastry brush dipped in the remaining 2 tablespoons oil, immediately brush both sides and sprinkle with Maldon salt.