If you are looking to impress, there are few foods that will convey the message "you are special" more than a rack of lamb. This one has two simple food processor pestos at play -- one for slathering that will make a nice crust, and one for serving. Frenched simply means very well trimmed of fat, with the bones scraped clean. You can do this yourself, or ask the butcher to do this for you. (Many butchers sell already-Frenched racks of lamb. They are pricy, but you're going for a showstopper here.)
Place a rack in the upper third of the oven and preheat the oven to 450 degrees F.
For the lamb with herb crust: Place the parsley, olive oil, mustard, rosemary, garlic, lemon zest and juice and a generous amount of salt and pepper in the bowl of a food processor. Puree until the mixture becomes a paste. Spread the mixture all over the lamb (try to avoid the bones and get it all on the meat).
Place the lamb on a rimmed baking sheet bone-side up, and roast until an internal thermometer reaches 130 degrees F for medium rare, 15 to 20 minutes. Transfer the lamb to a cutting board, cover loosely with aluminum foil and let rest for about 10 minutes.
For the mint-basil pesto: While the meat is roasting and resting, place the mint, basil, parsley, lemon juice, honey, garlic and some salt and pepper in a clean food processor bowl. Puree to a paste; scrape down the sides of the food processor once and process again. Transfer to a serving bowl with a small spoon to serve.
Slice the racks of lamb into either single or double chops. Serve with the pesto passed on the side.