Place lamb, vinegar, 1 rosemary sprig and minced garlic in a gallon size zipper-lock plastic bag. Seal and shake bag. Refrigerate over night.
Using S-blade, with food processor running, add croutons, rosemary leaves, 3 garlic cloves, salt and pepper to food chute. Process until fine crumbs are formed.
Preheat oven to 425°F.
Remove lamb from plastic bag; place lamb bone side down in roasting pan sprayed with nonstick cooking spray. Spread mustard on meaty side of lamb. Press crumb mixture into mustard.
Bake 30 to 35 minutes for medium-rare. Let stand 10 minutes before cutting.
Place lamb, vinegar, 1 rosemary sprig and minced garlic in a gallon size zipper-lock plastic bag. Seal and shake bag. Refrigerate over night.
Using S-blade, with food processor running, add croutons, rosemary leaves, 3 garlic cloves, salt and pepper to food chute. Process until fine crumbs are formed.
Preheat oven to 425°F.
Remove lamb from plastic bag; place lamb bone side down in roasting pan sprayed with nonstick cooking spray. Spread mustard on meaty side of lamb. Press crumb mixture into mustard.
Bake 30 to 35 minutes for medium-rare. Let stand 10 minutes before cutting.