Roast the cumin seed and asafetida on a dry pan till they turn light brown. If the Tatri is in big pieces then break it into smaller pieces.
Grind all the spices along with salt in a grinder. Your chat masala is ready. You can store this chat masala in an airtight container for up to 6 months. You can use this chat masala in chat and also in salads, soaked chickpea, sweet corn etc.