Something amazing happened in my kitchen tonight

Yesterday while at the market I saw a beautiful Australian Bone in leg of lamb at a really good price and couldn't help myself. You see i have a weakness for lamb. Lamb is definitely my protein of choice and nothing is better then a rustic roasted leg of lamb. Since i am still trying to loose the baby weight I trimmed off ALL the fat and I smothered both sides in Dijon mustard and salt, pepper and roasted garlic powder. Then i took a large onion and sliced it thickly and lined the bottom of my roasting pan with it and topped it with my seasoned leg of lamb. I preheated my oven to 450 degrees and roasted it for 10 minutes before dropping the temp to 350 and roasting 15 minutes per pound. After letting the meat rest I moved it to a platter and here is where there magic happened. I took all of those onions now infused with lamb juices and mustard and all of the drippings in the pan and i combined it all with a sliver of butter in the vitamix. This was the tastiest sauce i have ever had, it was mellow and oniony and gamey and delicious! My 4 year old ate 4 servings of meat! I will make this onion jus again and again!