There seem to be as many recipes that call for searing a rack of lamb first as those that call for skipping that step. I'm all for creating less mess, as long as the dish is tasty. Advice?
Personally, I think the searing step is important. It creates the tasty browned crust. I sear and roast in the same pan.
I usually don't sear a rack of lamb because I tend to coat it with an herb & bread crumb mixture (adhered with dijon mustard). If you don't coat the lamb with any season, I would sear for color and a nice crust. Your choice.
A friend of mine actually goes the extra mile and sears and then coats. Then roasts it in her wood fired brick oven that only gets used during winter. It's the best lamb that I've ever tasted.
I'm with HalfPint. I don't sear when I'm coating. But then maybe I should... ;)
I use Barbara Kafka's high heat method (without searing) in Roasting. Her recipe involves coating with herbs and crumbs but lately I don't even do that and it comes out great (without searing) every time.