Rather than the regular Biryani, Sindhi Biryani is more spicy and tasty. Don't know whether it originates from Sindh or not.
Just make sure about one thing if you don't want your rice overly cooked, keep on checking them while you r boiling them and drain them as soon as you turn off the heat. Do NOT leave them in the water once you turn off the heat.
You can also add some vinegar while boiling the rice so they won't stick together.
Note, you can also substitute mutton with chicken. Potatoes are not necessary if you use Chicken though.
P.S For Desi people the rice measurement is 5 tea cups and not mugs.