Add the potatoes to a pot and cover with 6 cups water. Season well with salt. Bring to a rolling boil over high heat and cook the potatoes until easily pierced with the tip of a sharp knife, about 9 minutes. Drain and cool, about 10 minutes. Peel and set aside.
Combine the granulated garlic, 4 teaspoons salt, the black pepper, cumin, cinnamon, fenugreek, turmeric and nutmeg in a small mixing bowl. Set aside.
Once cooled, crush the potatoes gently; the texture should be course and crumbly. Place into a bowl.
Thoroughly combine the egg, scallions, 1/4 cup of the flour and the spice mix in a bowl. Add to the potatoes and stir to combine. Season the remaining flour with 1 teaspoon salt and some pepper. Form the potatoes into 2 1/2-ounce patties. Sprinkle the tops and bottoms with the seasoned flour.
Set a large nonstick pan over medium-high heat and add 3 tablespoons oil. Once hot, fry the patties, in batches if necessary, on the first side until golden brown, about 3 minutes. Flip and place into the oven until crispy on both sides and hot through, another 3 minutes. Remove from the oven and cool slightly.
To serve, arrange the patties on a serving dish. Garnish with cilantro and serve with lemon wedges.