In a large pot, bring the water and salt to a boil. Whisk in the chickpea flour and sumac, stirring vigorously for 2-3 minutes or until all of the water is absorbed and there are only very small lumps. It will be the consistency of polenta. Remove the pot from the heat.
Line a rimmed baking sheet with parchment paper. Spread the batter onto the prepared pan in a ½-inch thick layer. It won't take up the whole pan, but almost. Set aside to firm up for 30 minutes.
Cut the mixture into rectangular 2x½-inch pieces.
Pour the vegetable oil into a large, deep cast-iron skillet. Turn the heat to medium-high. Once the oil is hot enough (it should sizzle the second a fry is put in the pan), add about 8 fries to the pan. Cook until they are golden brown and crispy on the outside, about 3-4 minutes. Remove to a paper towel-lined plate. Repeat with remaining fries. Sprinkle with aleppo pepper and serve immediately.
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