Your paruppu usili is likely dry and hard because the lentils were not soaked long enough, were overcooked, or the vegetable moisture wasn't properly incorporated. Soaking the lentils adequately and steaming the mixture gently are key to a soft, crumbly texture.
Paruppu usili's texture hinges on the moisture content and the cooking process. Here's a breakdown of why it might be dry and hard:
Insufficient Soaking: The lentils (typically toor dal, chana dal, or a combination) need ample soaking time to soften. If they aren't soaked for at least 3-4 hours (or preferably overnight), they won't grind into a smooth paste and will remain grainy, leading to a dry usili.
Overcooking: Over-steaming or cooking the lentil mixture for too long will dry it out. The goal is to cook it just enough so that the lentils are cooked through but still retain some moisture.
Lack of Moisture from Vegetables: The vegetables you add (beans, cabbage, etc.) contribute moisture. If you're using vegetables that are naturally drier, you might need to add a splash of water during the steaming process to compensate.
Improper Grinding: The lentil mixture should be ground to a coarse, slightly grainy paste, not a completely smooth one. However, if it's too coarse, it won't bind well and will result in a dry, crumbly usili. Adding a tablespoon or two of water while grinding can help achieve the right consistency.
Incorrect Lentil to Vegetable Ratio: Using too much lentil mixture compared to the amount of vegetables can also lead to dryness. Ensure a good balance between the two.
To ensure a soft and crumbly paruppu usili, try steaming the mixture in a perforated plate or idli steamer. This allows for even cooking and prevents the usili from becoming waterlogged, which can happen if steamed directly in a pan.