Heat ½ cup oil and add the meat and shan nihari mix. Fry until the oil separates from the masala.
Add 18 cups/3½ litres water and the bones. Stir and bring to a boil. Cover and cook undisturbed on low flame (beef 6 hours, goat/lamb 4 hours, chicken 3 hours).
Remove the bones, collect the marrow and discard the bones. Add the marrow to the gravy.
Gradually add the dissolved flour to the gravy. Stir to mix. Bring to a boil and cook for 15 minutes. Stir occasionally.
Heat the remaining oil and add the sliced ​​onions. Fry until golden and pour over the nihari. Cover and simmer on low flame for 10 minutes.
If desired, remove excess oil before serving