Rinse the masoor dal until the water runs mostly clear. Soak in plenty of water for 2 hours (or overnight in the fridge). The lentils should press soft between your fingers.

Drain thoroughly. Shake off excess water in a colander for a minute so the batter stays thick.

Add drained lentils, 1 tablespoon oil, ajwain, cumin, red chili powder, turmeric, hing (if using), and salt to a blender. Blend, adding water 1 tablespoon at a time, until you have a thick, smooth paste that spreads but does not pour. If it turns runny, blend in the optional rice flour or besan.

Preheat the oven to 350°F (175°C). Line a baking sheet with parchment and lightly brush with oil.

Scoop the batter onto the parchment. Spread into a thin, even rectangle about 1/8 inch thick (roughly 10x12 inches). Wet the spatula lightly if it sticks.

Score into squares or rectangles with a knife or pizza cutter. Sprinkle sesame seeds and press them in gently.

Bake 18 to 20 minutes, then check. If the center still looks pale and soft, bake 8 to 12 minutes more until the edges are golden and the surface feels dry and firm. Total time is usually 25 to 35 minutes depending on thickness and oven.

Cool on the parchment 5 minutes, then transfer the sheet (or broken pieces) to a wire rack. Cool completely. Snap along the score lines. Store in an airtight jar at room temperature for up to 1 week.