Reserved duck fat or melted unsalted butter, for brushing
In a medium bowl, mix the chickpea flour with the all-purpose flour and salt. Whisk in the milk until smooth. Whisk in the olive oil and let the batter rest for 30 minutes. Whisk in the water.
Lightly brush a 7-inch crêpe pan with reserved duck fat and set it over moderately high heat. Pour 3 tablespoons of the crêpe batter into the pan and swirl to coat the bottom. Cook for 1 minute, or until brown around the edge. Flip the crêpe and cook for 20 seconds longer. Transfer to a large plate. Repeat with the remaining batter.
The crêpes can be cooked up to 4 hours ahead; stack and let stand at room temperature.
Chickpea flour is available at ethnic food stores. At Indian groceries, it's called besar.