Finely chopped large onions, minced the cloves of garlic and soak the red chillies in water for 20 minutes.
Add the finely chopped onion, saute for a while till it becomes translucent. Add the ginger and garlic, continue saute on medium heat.
This is a slow braising meat dish, and more you braise it, more it will taste better.
I cook mutton in big dekchi or deep bottom vessel. But you can use pressure cooker to save time and fuel.
If the meat is tender enough and release enough juices, then no need to add water. Or adjust the amount of water accordingly. However, I do not prefer to add water.
Large onions means really large (US standard) , so adjust the amount of onion accordingly.
I have used pearl onion for garnish, and has chopped few of them and add it to the dish. This is optional.