Making the Dough:

• In a large mixing bowl, whisk the flour, sugar, salt, garlic powder, oregano and basil. Using a pastry cutter, fork, or your hands, cut the butter into the flour mixture, forming pea-sized crumbs. Add the ice water, starting with 6 tablespoons and adding 1 tablespoon at a time if needed to form a dough ball, being careful to not overmix. Form the dough into a flat circle and wrap in plastic wrap. Chill in the refrigerator for 30 minutes.
• While the dough is chilling, saute the vegetables. Dice the onion. Slice the zucchini down the middle lengthwise, and then thinly slice each half. In a large pan, add the olive oil over medium high heat and saute the vegetables for 5 minutes, until they begin to soften. Add the minced garlic and cook for an additional minute, until the garlic becomes fragrant. Season the vegetables with salt to taste.
• Preheat oven to 400° F.
• On a lightly floured surface, roll the dough out into a 15-inch circle about ¼ inch thick. Carefully transfer the disc to a parchment paper lined baking sheet.
• Spread the pesto onto the rolled out crust starting in the center. Work your way out, leaving a 2-inch border around the edge of the dough. Using a slotted spoon, spread the vegetable mixture over the pesto. Fold the border up and over the filling, pleating as needed. Its ok if the crust is imperfect! Top the galette with the mozzarella.
• In a small bowl, whisk the egg with 2 tablespoons water. Using a pastry brush, brush the egg wash all over the sides of the crust. Bake the vegetable galette for 45-50 minutes. In the last 20 minutes of baking, tent the galette with foil so the mozzarella doesn't brown too much. Let cool on a wire rack for 10 minutes before serving. Then, EAT!