1. Preheat the oven to 325 degrees F.
2. Grind together the cumin, fenugreek (if using), coriander, and black pepper in a spice grinder or coffee grinder. Move to a small bowl, and mix in the turmeric and salt. Mix in the ghee to form a seasoned paste. Rub all over the chicken, including under its skin.
3. Place the chicken on a rack in a roasting pan. Tie together the wings and legs and place in the oven. Roast until the internal temperature at the thickest part of the breast and leg is 150 degrees F. Remove from the oven and let sit for 15 minutes.
4. While the chicken is roasting, add the potatoes to a medium pot and cover with water. Boil until tender, about 8 minutes. Drain and rinse under cold water. Pat dry with a paper towel. In a medium nonstick skillet over medium-high heat, add the canola oil. Once the oil is hot, add the potatoes and mustard seeds and stir occasionally until golden brown. Season with salt.
5. Place the chicken on a platter and garnish with the potatoes. Serve.