Mediterranean Spelt Flatbread

Preheat the oven to 400 degrees F. Coat a large baking sheet with cooking spray. Set aside. Add the yeast to warm water and let sit for 5 minutes. The yeast should be foamy. Whisk in the egg and salt, then stir in flour to form a ball. Dough will be sticky. Set aside, covered. Toss yellow bell pepper, grape tomatoes, arugula, and feta cheese with olive oil, balsamic vinegar, and black pepper. Dust your hands with additional spelt flour and spread the dough onto a baking sheet to form about a 9-inch x 13-inch rectangle or larger. The dough should be relatively thin.  Pour the vegetable mixture evenly over the dough, leaving about ½ inch around the edge. Bake for 20 minutes, then cut into 8 pieces.