Mix the beetroot paste with the batter and keep aside. To make the dosa, heat a tawa / griddle. Drizzle 1/2 tsp. oil and spread around. Sprinkle some water. After it sizzles off, wipe dry with a tissue paper. This ensures a non-stick coating.
Pour a ladle of the batter and spread in a circular motion with the back of the ladle. Drizzle some oil around the edges and over it. Fry for a minute or two on low flame till one side turns light brown.
Flip it over and cook the other side too. Make similar dosas with the remaining batter. Each time you make a dosa, rub a cut onion on the tawa for easy removal of the dosa. Serve them hot with sambar and coconut chutney.