Plain Dosa is the unfilled form of the South Indian crepe: a thin, crisp pancake of fermented rice-and-lentil batter, cooked on a griddle and served with chutneys and sambar, with nothing rolled inside. The angle is purity. Without a potato filling to carry it, the dosa has nowhere to hide, so the quality of the batter, the fermentation, and the griddle work are the entire dish. It is the cleanest test of whether a kitchen can make dosa at all.
The make begins long before the griddle. Rice and urad dal are soaked separately, ground, combined, and left to ferment until the batter rises, smells faintly sour, and develops the structure that gives a dosa its tang and its lace. At service the batter is poured onto a hot, lightly oiled tawa and spread from the center outward in a quick spiral with the base of a ladle, thin and even. Oil or ghee is drizzled at the edges, and the dosa cooks undisturbed until the underside turns deep golden and crisp and the top sets dry; it is then folded or rolled and served at once. The result wanted is a crepe that is crisp and evenly browned, with no pale gummy patches and no raw batter smell, carrying a clean fermented tang. Good execution produces an even, lacy or smooth golden surface and a dosa that stays crisp the first minutes on the plate. Sloppy versions show up as under-fermented batter that tastes flat and bready, uneven spreading so the round burns at the rim and stays raw at the center, or a poorly seasoned griddle that makes the dosa stick and tear into a mess.
It is served with a set of accompaniments that complete it: coconut chutney, often a tomato or other chutney, and a bowl of hot sambar for dipping and pouring. The filled masala version, the moong-based pesarattu, and the steamed idli are separate members of the same South Indian family, and each deserves its own article rather than being crowded in here.