Take sooji or semolina. If it is a thin semoline like one common in north india, mix it in curd. It dissolves easily, but in south india there are many types of semolina available and few are really big sooji dana. IN case of that, mix it with curd and blend it to make a fine paste. The consistency of the rava batter should be flowing but not too watery. Adjust the water now.
Chop onion, green chilli, coriander leaves and ginger in a different bowl and mix well. Add salt in the mix now but do not leave this vegetable mix for long else it will become watery.
Heat a tawa and spread a ladle full of rava batter on the hot tawa. Spread a handful of onion mix on the top of the batter on dosa tawa.
Now flip the side of rava uttapam and cook from the bottom as well. This is an easy recipe for rava onion uttapam. Once rava uttapam is taken off from the tawa, sprinkle lemon juice over the tawa and clean it with a cottoon cloth and repeat the process for rest of the batter.
Serve hot rava uttapam with coconut chutney and red chutney.