If the tripe doesn't already come cleaned from the mutton shop, blanch it in hot water with salt for 10 minutes to remove the undigested parts of food lodged in the animal's stomach. Then rub the vajri (tripe) with rice flour till its perfectly clean. Rice flour is grainy and helps in getting the dirt out. Rinse out the rice flour and repeat the process 3 to 4 times till the tripe is clean. If the dirt is stubborn, use a toothbrush to get it out before rinsing.