Step 1

Put the all-purpose flour, rye flour, baking powder and salt in a food processor and pulse until blended. Pour the club soda into a measuring cup and add the vinegar. Pour the liquid into the processor as it is running and mix until the batter is very smooth. Let sit for 10 minutes.

Step 2

Heat a 10-inch nonstick skillet over medium heat. Spray the skillet with a thin coating of nonstick spray. Make the injera the way you make a crepe: Remove the skillet from the heat and tilt the edge farther from you down toward the floor. Pour 1/3 cup of the batter in a pool slightly off-center further from you, and then quickly swirl the pan so that the batter covers the entire surface. Place the pan back on the heat, cover with a lid and cook until the edges start pulling from the pan and the top is shiny and slightly dry, 90 seconds to 2 minutes. Peel the injera from the pan and transfer to a plate, top-side up. Serve cool.