How to French trim a rack of lamb is one of the first skills you learn as a chef, but it's one home cooks are keen to pick up too. A clean rack of lamb says, 'I know what I'm doing in the kitchen.'
The purpose of French trimming is wholly aesthetic: any meat left on the bones will make them look dirty after cooking. There are different ways of doing it, some chefs, for example, use twine to help clean the bones, but Gordon Ramsay relies solely on his knife, as you can see in the clip below.
It's a technique where practice makes perfect, but when you've been doing it as long as Ramsay, you can whizz through it. Ramsay just set a world record for filleting a fish too. Say what you want about Ramsay, but his knife skills are on point.