1. Ask the butcher to dress the mutton leg properly while purchasing.
2. The mutton leg aka mutton raan should have dip slits on it.
3. 

Marination stage 1 (before 48 hours of making the roast)

1. Wash and clean the mutton led and pat dry it.
2. The mutton leg should be at room temperature.
3. Dry roast Dry Red Chilli, Black Cardamom, Star Anise, Green Cardamom, Ajwain, Cumin Seed, Mace, White Pepper, Cinnamon stick, and also Coriander Seed.
4.  
5. 
6. Keep the flame low while dry roasting the spices.
7. Switch the flame off when the spices emit an aroma.
8. Wait till the temperature drops completely.
9. Now make a coarse powder of the spices.
10. Mix Ginger and garlic paste and also salt with this mixture to make a semi-thick paste.
11. Add Mustard oil to this mixture and mix well.
12. Apply this mixture to the mutton raan properly, especially within the slits. 
13. 
14. Once done, cover the mutton leg with cling film or plastic wrap and keep it in the freezer (not in the refrigerator) for at least  24 hours. 

Marination stage 2 (before 8 hours of roasting)

1. You need to take this out from the refrigerator at least 1 hour before roasting. 
2. Mix Plain Yogurt, Turmeric Powder, Cumin Powder, Coriander Powder, Red Chili Powder, Garam Masala Powder, Sugar, Salt, and Mustard Oil to make a thick paste.
3. 
4. Now apply half of the marinade to the mutton leg and keep it in the freezer for 8 hours.
5. Do not forget to apply the marinade within the slits.
6. 
7. Keep the remaining marinade in the fridge.

Before Roasting the Mutton Leg

1. Take the mutton leg out of the freezer for at least 1 hour before roasting.
2. Take out the remaining marinade as well.
3. Add 1 Tbsp. Ginger Paste and  1 Tbsp. Garlic Paste to it.
4. Add 1 Cup of Onion Crisp aka Piyaj Beresta to this mixture as well.
5. 
6. Apply this mixture to the marinated Mutton Leg and keep it as it is at room temperature for at least 1 hour (preferably 2 hours) before roasting.
7. Do not forget to apply the marinade within the slits.
8. 
9. Meanwhile, cut 8 onions and 8 tomatoes into four pieces each.
10. 
11. Make a sturdy oven-safe tray ready.
12. Place the mutton leg in the tray.
13. Fill the sides with chopped onion as well as tomatoes.
14. Pour the remaining marinade on top of the mutton.
15. Melt 50ml Ghee and pour it over the mutton.

Roasting the Mutton Leg

1. Preheat the oven to 140 degrees C for 15 minutes.
2. Cover the mutton with aluminum foil.
3. Roast it after keeping the cover on the lowest temperature of the oven for 2.5 hours.
4. Remove the foil after 2.5 hours and keep roasting for 30 minutes at 140 degrees C.
5. Check with a toothpick whether the same is coming out clean or not; if yes, the mutton raan is fully roasted, if not keep roasting for a few more minutes.
6. 
7. Once done, switch the oven off.
8. Take the roasted mutton raan out after 15 minutes.
9. Be ready with a Steak Knife while serving the Roasted Mutton Raan!