Season Leg of Lamb (1) with Freshly Ground Black Pepper (to taste), Kosher Salt (to taste), Cayenne Pepper (to taste) and Granulated Garlic (1 pinch). Sear on all sides until golden brown.
Transfer to a rack or grill pan, roast in oven at 290 degrees F (145 degrees C) for about 90 minutes for medium to medium well, depending on the size of the leg and your preference.
When cooked to your liking, set aside for at least 20 minutes to let the juices re-distribute.
Slice according to your preference.
Slice Potato (3) and then blanch them by putting them into boiling water for 2-3 minutes.
Drain the potatoes, then sauté them in Duck Fat (to taste) with Kosher Salt (to taste) and Cayenne Pepper (to taste).
Saute sliced Yellow Onion (to taste) in Duck Fat (to taste) with Kosher Salt (to taste) and Freshly Ground Black Pepper (to taste).
Add the juices which have collected from the resting lamb leg to the yellow onions.
Add the Guinness® Stout Beer (12 fluid ounce) to the yellow onions and simmer until onions are soft but not mushy.
Plate the lamb and the potatoes.
Add the onion marmalade and a few dollops of Nonfat Plain Greek Yogurt (to taste) and enjoy!