You can also think of Lamb Noisettes as lamb T-bone chops with the T-bone removed. They have a bit of tenderloin in it, and a bit of eye of loin (which is next to the tenderloin.) They will be about 2 inches (5 cm) thick, though North American cut ones tend to be larger.
Good butchers will sell them with a ring of fat around them. This protects them as they cook, in the same way that filet mignon is often cooked with bacon wrapped around it.
Depending on how thick they are cut, they will weigh anywhere from 1 1/2 oz (40g) to 3 oz (90g.)
Allow 2 per person as they are quite small.
Use for dry-heat cooking: pan-frying, broiling (aka grilling in the UK) or grilling (aka BBQ outside the US).
Cook 10 to 12 minutes, turning once half way through.