Soak the Dal: Pick through the moong dal for any debris, then rinse thoroughly.
Place the dal in a large bowl and cover with at least 2 inches of water.
Let it soak for 8 hours or overnight.
Once soaked, drain the dal completely in a fine-mesh strainer and do not rinse it again.
Grind into a Fluffy Paste: The goal is a thick, airy paste using minimal water.
In a food processor or high-speed blender, grind the drained dal in batches.
Add water just 1 teaspoon (5 ml / 0.2 fl oz) at a time only if needed to get the blades moving. Scrape down the sides frequently until you have a smooth, fluffy, and thick paste.
Season and Rest: Transfer the paste to a mixing bowl. Gently fold in the salt, minced green chilies, and baking soda. The batter should be thick enough to hold its shape. If it seems too runny, stir in the optional flour, one tablespoon at a time.
Cover the bowl and let it rest in a warm spot for 4 hours to ferment slightly.
Shape the Badis: Lightly grease a few baking sheets or large steel plates.
Using your fingertips or two small spoons, drop scant teaspoon-sized dollops of the batter onto the prepared trays, leaving a small gap between each one.
Dry the Badis: The badis must be dried until completely hard and brittle. For traditional sun-drying, place the trays in direct sunlight for 2-4 days, covering them with a net to protect from dust.
Bring them indoors at night and flip them after the first day. Alternatively, use an oven at its lowest setting (150-170°F / 65-75°C (165°F)) with the door ajar for 6-10 hours, or a dehydrator for 8-12 hours.
Store and Use: Test for doneness by breaking a badi in half; it should snap cleanly. Store the completely dry badis in an airtight container at room temperature for several months. To use, pan-fry them in a little oil until golden, then add to curries, soups, or rice dishes to simmer and soften.
Patience is Key: Ensure the badis are bone-dry before storing. Any residual moisture can lead to mold. They should snap cleanly when broken; if they bend, they need more drying time.
Fry Before Use: For the best flavor and texture, always pan-fry the dried badis in a little ghee or oil until golden brown and fragrant before adding them to your main dish.