Mix olive oil, italian seasoning, garlic, walnuts, orange juice, salt and pepper in a bowl. Dip lamb chops into mixture to coat evenly. Cover chops and refrigerate for at least 30 minutes. If using oven, preheat to 425 F (which you can do while the chops are marinating). You may want to put a cooking rack half full with water on bottom rack to catch future dripping from the chops. Place lamb chops on top rack and change the oven to broil. Grill between 5 to 10 minutes per side, depending on desired doness.
I have not measured the ideal inner temperature for the chops, so if you find it, feel free to share.
You can do grilled tomatoes ‘a la provencal’ to go with the chops. Quick steps: cut fresh tomatoes in half to separate top from bottom, arrange in an aluminum-foiled covered (for ease of cleaning later) cooking rack with the cut side of the tomatoes on top. Mince onion and garlic and spread on top of the tomatoes. Add french ‘herbe de Provence’, salt and grounded black pepper. Cook along with lamb loin chop – careful the tomatoes will cook faster than the loin, they should be browned but don’t let them burn.