Onion Rava Dosa is the South Indian semolina dosa made with onions worked through it, a thin, intensely lacy, crackly disc that behaves nothing like a spread fermented dosa. The angle is the batter and the lace it produces. A rava dosa uses no fermentation and no urad dal; it is a pourable slurry that builds its open, net-like structure from how it is splashed onto the heat, and the onion rides along inside that lattice, frying crisp in the gaps. The result is the most fragile and brittle dosa on the tiffin menu, closer to a savory rice-and-semolina cracker than a soft crepe.
The build runs on a thin, almost watery batter of fine semolina, rice flour and a little plain flour, loosened with water and seasoned with cumin, crushed pepper, green chili, curry leaves and chopped coriander, then rested briefly so the rava hydrates. Finely chopped onion is stirred in, or scattered on as the dosa cooks. The defining technique is the pour: instead of spreading with a ladle, the cook flings and drizzles the loose batter across a hot, well-oiled tawa from a height, deliberately leaving holes so the disc sets as a lace rather than a sheet. The batter must be stirred between every pour because the heavier flours sink fast and a settled batter gives a flat, dense dosa with no holes. Ghee or oil goes around and into the gaps, and it is cooked until deep gold and crisp enough to crackle, then folded or rolled. Good execution is shatteringly crisp with a fine even lattice and onion that has fried sweet and brown in the holes. Sloppy execution is a batter gone thick and unstirred giving a heavy pancake, onion added so thick it stays raw and wet, or a pan not hot enough so the lace never forms and the whole thing turns leathery.
Variation is mostly about additions and accompaniment. A masala rava dosa tucks potato filling inside; cheese or extra pepper versions are common; the spice line shifts with the cook's hand on chili and curry leaf. It is served hot and immediately, with coconut chutney and sambar, because it goes soft within minutes of leaving the heat. This is a distinct thing from the spread, crisp-edged griddle dosa with raw onion pressed onto it, and from the soft thick uttapam; both take onion in their own way and deserve their own articles rather than being crowded in here. Onion Rava Dosa is judged on lace and crackle: a true open net, brittle to the touch, with the onion fried into it rather than sitting raw on top.