Wash the idli rice and urad dal together in several changes of water until the water runs mostly clear, then drain.

Soak the rice, urad dal and fenugreek seeds together in enough water to cover by 2 inches, and soak the poha separately in a little water 20 minutes before grinding.

Drain the soaked rice and dal, then grind together with the soaked poha and just enough fresh water to a smooth, thick, pouring-consistency batter.

Transfer the batter to a large container, cover loosely, and leave in a warm place to ferment until doubled in volume and visibly bubbly on top.

Gently fold the salt, sugar and sooji into the fermented batter without deflating it, adjusting with a little water to a thick, spreadable consistency.

Let the seasoned batter rest so the sooji softens and absorbs moisture, which gives the finished dosas their characteristic sponginess.

Heat a flat tawa over medium heat and test readiness by sprinkling a few drops of water on it — they should sizzle and evaporate immediately.

Pour a ladleful of batter onto the center of the hot tawa and spread it gently in a thick circle, unlike a regular dosa, without thinning it out.

Drizzle a little oil around the edges, cover with a lid, and cook until small steam holes appear across the surface and the edges start to lift.

Flip the dosa carefully and cook the other side briefly until just set, since set dosa is not meant to be crisp like a regular dosa.

Remove the dosa from the tawa, stack two or three together as a set, and repeat the pouring and cooking process with the remaining batter.