I am sure this is an intriguing post to many about a rasam upma !.there is nothing mysterious about the dish, just the humble upma made with left over rasam .Why left over rasam ? because in many Tamil households, rasam is an integral part of the menu and in many cases it is left over at the end of the day..so a novel way of finishing off as dinner would be to transform the rasam to rasam upma.
Now I leave it to you to choose to make rasam specially for the recipe or use what ever is left over making adjustments for flavors. This is just an idea .
I use the left over rasam boil it adding little more water and salt added roasted rava according to rasam qty for example for 2 cups boiling rasam add one cup roasted rava , chopped dhaniya leaves 1-2 tsp coconut oil cover and cook on low flame till rava absorbs rasam . Then stir well to prevent lumps . That s it it !.You could also make rasam upma by roasting rava, adding rasam ingredients one by one to the boiling water.
I prefer to use up previously made rasam though.