Preheat grill to 375˚F. (over high heat)
For the sauce: Place all ingredients into a food processor and whip until smooth. Adjust seasonings and set aside.
French the ribs of the rack (unless you’ve already had a butcher do so for you) and wrap the tips of each rib with about an inch of aluminum foil.
Place the thyme, oregano and rosemary into a small bowl and toss together. Set aside.
Once the grill is hot, brush both the rack and grill with extra virgin olive oil and generously season the rack with herb mix, salt and pepper, on both sides.
Place rack on the grill, fat side down and sear for about 4 minutes. Flip the rack and continue to sear for 2 to 3 minutes. Reduce the flames to medium and cover the grill. Allow the rack to grill with the cover closed, for about 6 to 8 minutes (keeping a close eye out for flame ups), uncover the grill allow the rack to continue to cook for another 1 to 2 minutes. This will give you medium to medium-rare results. For a medium to medium-well rack of lamb, keep grill cover closed for 8 to 10 minutes.
Remove from heat and transfer the lamb onto a cutting board and loosely cover with foil. Allow the lamb to rest for about 10 minutes before slicing and serving.
Serve rack with sauce and roasted radishes.