Hello! The reason your lentils are still tough is likely due to two factors: adding salt at the very beginning of cooking, which toughens the outer skin, and potentially using old lentils that have lost their moisture.
To save your dinner ulam and your LPG, here is what you can do:
1. Pressure cook: Transfer them to a pressure cooker for about 10-15 minutes.
2. Add baking soda: A tiny pinch of baking soda will raise the pH and speed up softening, though use sparingly.
Avoid adding salt or acids like tomatoes at the start next time!