Preheat oven to 450 degrees F (230 degrees C). Remove Leg of Lamb (4 pound) from marinade, letting excess drip back into bag.
Place lamb on a plate, and season generously with Garlic (1 head), Fresh Rosemary (3 sprig), Salt ( to taste) and Ground Black Pepper (to taste).
Pour marinade into roasting pan and add Mixed Vegetables (2 cup). Toss with Extra-Virgin Olive Oil (1/2 cup) and season with Coarse Salt (to taste) and Ground Black Pepper (to taste).
Arrange the seasoned leg of lamb on top of the vegetables.
Then cover with foil and reduce oven temperature to 300 degrees F (150 degrees C) and cook until medium-rare. About 1 1/2 hour. An instant-read thermometer inserted in the center should read 125 degrees F (52 degrees C) when inserted in the thickest part of the lamb.
Allow leg of lamb to rest for 20 minutes before slicing. Toss vegetables with pan juices. Serve and enjoy!