How to Make It
In a large bowl, combine 1/2 cup of the water with the yeast and sugar and let stand until foamy, about 5 minutes. Add the remaining 1 1/2 cups of water, 5 cups of the flour and the kosher salt and stir until a stiff, crumbly dough forms. Scrape the dough out onto a lightly floured work surface and knead until smooth and elastic, about 5 minutes; add more flour as necessary to prevent sticking. Divide the dough into 6 pieces and form each piece into a ball. Lightly brush each ball with olive oil and transfer to an oiled baking sheet. Cover with plastic wrap and let rise until doubled in bulk, about 1 hour.
Meanwhile, in a small saucepan, combine the 1 cup of olive oil with the garlic and rosemary and cook over moderate heat until the garlic begins to sizzle, 2 minutes. Remove from the heat; let cool. Discard the garlic and rosemary.
Set a pizza stone on the bottom shelf of the oven. Preheat the oven to 500°, allowing at least 45 minutes for the stone to heat. Alternatively, lightly brush a large baking sheet with olive oil and sprinkle it with cornmeal. Punch down the balls of dough, cover with plastic and let rest for 15 minutes.
On a lightly floured surface, working with 1 ball of dough at a time and keeping the rest covered, stretch or roll out the dough to an 8-inch round. Transfer the dough round to a lightly floured pizza peel. Brush it lightly with garlic oil and sprinkle with sea salt. Slide the round onto the stone and bake for 5 to 6 minutes, or until golden. If using the baking sheet, transfer 2 of the rounds to the sheet and bake for 10 minutes, or until golden. Remove the baking sheet from the oven and bake the flat breads directly on the oven rack for 2 minutes longer. Transfer the flat breads to a rack and repeat with the remaining dough.
In a large bowl, whisk the lemon juice with the mustard and vinegar. Whisk in the olive oil and season with salt and pepper. Add the baby greens, herbs and scallions and toss to coat. Mound the salad onto the flat breads, sprinkle with the goat cheese and serve.