In a large bowl, combine the all-purpose flour, gram flour, if using, yeast, and sugar and mix well. Make a well in the center of the flour mixture. Pour the oil, almost all of the water, and the food coloring, if using, into the well and stir until no lumps remain. The texture should be slightly runny, like pancake batter. (This is also known as "ribbon consistency," which simply means that when the batter drips from a spoon, it falls like a ribbon onto the batter that remains in the bowl.) If necessary, add a touch more water. Let the batter rest at room temperature for 20 minutes.