In a large bowl, combine the flour and salt. Add the warm water and 2 tablespoons of olive oil, and knead until a smooth dough forms.
Cover the dough and let it rest for 30 minutes.
In a skillet, heat 1 tablespoon of olive oil over medium heat. Add the sliced onion and cook until softened and lightly browned, about 10 minutes.
Roll out the dough into a large rectangle, about ¼ inch thick.
Spread the cooked onions over the dough, leaving a 1-inch border. Sprinkle with the dried oregano and red pepper flakes.
Starting from the long side, tightly roll up the dough into a log.
Slice the log into 1-inch thick pinwheels.
Place the pinwheels on a baking sheet and bake at 400°F for 15-20 minutes, or until golden brown and crispy.
