Preheat the oven to 400˚. Rub lamb on all sides with olive oil and season with salt and pepper. Position lamb in a roasting pan, meaty side up, and place in oven for 10 minutes.
While lamb is cooking, combine parsley, garlic, orange zest and pecans in a bowl.
Remove lamb from oven. Spread all sides with Dijon mustard (but keep it off the bones), and then coat with herb and nut mix, gently pressing it into the mustard.
Return to oven, and continue to cook for an additional 10 minutes or to desired doneness.
Notes
Bonus recipe tips from Chef Adam Moore:
You can leave the fat on the rack; there’s usually still a lot of good meat in it.
Any fine-grain or spicy mustard will work, but heavily seeded mustards don’t hold the crust on as well. Mayonnaise or yogurt are also good stand-ins for Dijon.
The texture of the chopped pecans should resemble coarse sand. Or if you don’t want to use nuts, you can swap in finely chopped pepitas or grated Parmesan.
For more citrus flavor, squeeze the juice from the zested orange over the top of the meat when it comes out of the oven, before you add the crust.
For a nice presentation, wrap the protruding bones with foil to keep them from discoloring.
Roasted sweet potatoes make for a delicious side. For a beverage pairing, try a light red wine or a zesty white.