Into a mini-prep food processor add bread mint and rosemary. Pulse until fine crumbs are formed. Set aside.
Season lamb with salt and pepper.
In a large grill pan or cast iron pan, heat olive oil over medium-high heat. Add lamb, fattier side down and cook for 1-2 minutes to sear. Flip lamb over and cook for an additional minute. Remove from heat.
Spread mustard on fattier side of lamb.
Top mustard with bread crumbs - pressing down slightly to adhere.
Roast lamb for 18 minutes for medium rare. (20 minutes for medium).
Remove from pan and let rest for 4-5 minutes on a cutting board.
Carve into 2-rib portions.
Video
Notes
Rosemary leaves are tough and don't get minced well in the food processor, which is why I chop them before adding them to the bread mixture.