Heat a flat pan/dosa tawa and set it on medium flame. Take a big ladle full of dosa batter and pour it on the hot pan. Quickly spread the dosa batter into a thin circle. Sprinkle few drops of oil all around. Take 2-3 tablespoon of Pav Bhaji and place it at the center.
Spread Pav Bhaji all over the dosa and let it cook until the bottom is golden brown. Sprinkle some finely chopped onions all over the Pav Bhaji spread on the dosa. If adding, sprinkle grated cheese on top. Once the dosa is golden brown on the bottom, gently remove it from the pan by loosening the sides. Fold each end towards the center. Remove from heat. Repeat the same with rest of the batter.