Clean the rib bones well by scraping off meat and sinew with a small sharp knife. Cut the racks in 1/2 so that each has four ribs. Mix together the olive oil, crushed garlic, crushed rosemary and thyme sprigs in a large bowl. Add the lamb and coat well. Grind some coarse black pepper over all. Wrap well and marinate the racks overnight.
The next day remove the lamb from the marinade and scrape off as many herbs as possible. Preheat the oven to 400 degrees F.
Heat a large saute pan over medium-high heat and add 2 tablespoons of olive oil. Season the lamb well with salt; no additional pepper should be necessary, and sear fat side down until golden, about 7 minutes. Turn over so that the fat side is up and roast in the preheated oven for 20 to 30 minutes. Let the rack rest for 10 minutes before cutting.
To serve, cut each lamb rack into 4 equal pieces, 2 bones per chop and serve on individual plates or a platter with the accompaniments of your choice.