Roast lamb.
One of my favorite main dishes is roast lamb - I love a six-bone rack of lamb, rubbed with salt and pepper and brushed with mustard, roasted so that the fat crisps up, browns, splits and crackles. Done just so, the meat is soft and juicy, the flavor delicate and warm.
The simplicity of this is what makes it work, makes it go with anything - and like so many things, simplicity is in the details. Get good lamb. Get good mustard. Get a probe thermometer. Get an oven thermometer.
Pay attention to the little things, and the big thing will come out perfectly roasted, browned, gorgeous and tender and just the right thing for a cool summer night.