Pre-heat oven to 375 degrees. In a deep cooking/braising pan heat olive oil. Marinate racks of lamb in a pan, season with salt & pepper. Add garlic, dried mustard, sear lamb in hot olive oil, use caution. Sear well, till brown and crusty on both sides. Remove lamb, place lamb in a shallow cooking pan. Turn off heat in pan, deglaze with red wine, add thyme and lavander. Pour redwine over lamb, place in hot oven for about 20 minutes, till lamb reaches a temperature of 125 degrees. Remove from oven, place lamb on a cutting board. Let rest 5 minutes. On a stovetop, heat a saute pan, add the wine juices, reduce over medium heat. Turn off heat, add butter and incorporate. Slice the lamb, serve on plates with the wine jus.