How to Make It
In a blender or large food processor, blend the egg with 1/4 cup of oil until foamy. Add the salt and half of the water and pulse for 3 seconds. Add half of the chickpea flour and process until smooth. Add the remaining flour and water and process until smooth. Pass the batter through a fine mesh strainer into a bowl, stirring and scraping until all of the batter is through. Cover and refrigerate overnight or for up to 2 days.
At least 1 1/2 hours before baking, set a pizza stone in the center of the oven and preheat the oven to 500°. Lightly brush a 12-inch cast-iron skillet or deep-dish pizza pan with olive oil.
Whisk the batter until blended and pour it into the skillet. Bake the bread for 30 minutes. Brush the top of the bread with olive oil and cover two-thirds of it with a baking sheet. Turn the oven off and bake the bread in the residual heat for about 20 minutes longer, until deep golden brown and nicely glazed.
Using a spatula, loosen the edges and bottom of the bread, and slide it onto a work surface. Cut into small rectangles, sprinkle with cumin or harissa and serve hot or at room temperature.