Trim excess fat from leg of lamb and transfer the leg to a roasting pan.
Using a knife, make 6 shallow incisions into the leg and set aside.
In a small shallow bowl combine 6 cloves garlic, 1/4 teaspoon olive oil, thyme leaves, salt, and pepper; using the back of a fork, press into the garlic to mash it, and stir around to combine it with the rest of the ingredients. If you have a mortar and pestle, use that to make the mixture.
Stuff the garlic-herb mixture into the incisions. Set aside.
For the Paste
In a mixing bowl combine lemon juice, olive oil, paprika, fresh ground pepper, cumin, cayenne pepper, rosemary, thyme leaves, and minced garlic; mix until thoroughly incorporated.
Set aside two tablespoons of the paste. Cover and refrigerate.
Use the rest of the paste to rub all over the lamb leg.
Sprinkle lemon zest over the leg of lamb.
Cover the lamb with foil and let stand 4 hours in a cool place, or overnight in the refrigerator.
Preheat the oven to 350˚F.
Remove the lamb from the fridge and let it sit on the counter for 20 minutes before cooking. Set it on a roasting pan or a baking sheet.
Cut up the potatoes and arrange them around the leg of lamb.
Drizzle a bit of olive oil over the lamb and the potatoes; toss the potatoes to coat.
Take the reserved marinade/paste and, using a pastry brush, brush the paste over the potatoes.
Sprinkle coarse salt over the potatoes and lamb.
Roast for 1 hour and 10 minutes, mixing through the potatoes few times during cooking.
After 1 hour, check for doneness; Lamb is cooked through at 145˚F. For medium-rare, remove lamb from the oven at between 125˚F and 130˚F.
Remove from oven and let the meat rest for 20 minutes before carving.