Til Pitha (Assamese Sesame-Filled Rice Rolls)

Instructions

1. Rinse the glutinous rice (bora saul) and soak it in water for at least 6 hours or overnight. Drain it in a colander for 30 minutes, until no water drips but the grains are still damp.
2. Grind the damp rice with the salt in small batches in a dry grinder to a fine, slightly moist flour, then sift it. It should hold its shape when squeezed in your fist and crumble when pressed. Keep it in a covered container under a damp cloth so it does not dry out.
3. Make the filling: toast the black sesame seeds in a dry pan over medium-low heat, stirring, until they crackle and smell nutty, 3 to 4 minutes. Cool for 10 minutes, then grind them coarsely and mix with the finely grated jaggery until the mixture clumps together.
4. Heat the cast-iron tawa over medium-low heat until you can feel the warmth with your palm about 6 inches (15 cm) above it, about 5 minutes. Do not grease it.
5. Sprinkle about 2 tbsp (25 g) of the rice flour on the tawa in an oval about 5 by 3 inches (13 by 8 cm) and press it lightly with your fingertips or the back of a spoon into an even, thin layer.
6. Within 30 to 60 seconds the flour fuses into a pale sheet that holds together. Spoon about 1 tbsp of the filling in a line down the center.
7. Using a thin spatula, lift one long edge and roll the sheet into a cylinder around the filling, pressing the ends lightly. Push it to the cooler edge of the tawa for 30 seconds to firm up while you start the next one; the sheet should stay pale, with no browning.
8. Cool the til pitha on a plate for at least 15 minutes; they turn crisper as they cool.