In the last step, after the water is reduced, you will see the oil floating on top. That is the indication that your Mutton recipe is done and ready to serve.
People who are not used to seeing so much oil, floating on top, need not worry about health, since all the thokku recipes in south india, which tastes like pickle, are prepared with Sesame oil. This oil is healthy and can be consumed with so much oil floating on top.
Just make sure you are either using Wood pressed oil or cold pressed oil and not refined sesame oil.