Preheat the oven to 200°C.
Meanwhile, season the lamb well with fine salt.
Place a heavy frying pan over a medium-high heat. When it is hot, add the olive oil.
Put the lamb into the pan and colour it all over, turning it so that all sides brown evenly.
Put the lamb on a roasting tray and brush the meat with the violet mustard, then place in the oven and roast for 8 to 10 minutes. Remove and rest for 5 minutes in a warm place over the stove.
In another frying pan over a medium heat, add olive oil, the chopped shallots and cook for 1 to 2 minutes.
Add the pancetta and lightly colour.
Then pour the chicken stock to cover the pancetta and shallots. Bring to a simmer and reduce by half. Check the flavour and season well.
Add the carrots, peas and butter, and season with salt and pepper to taste.
Once you get the sauce consistency right, add the lettuce and mint. Let it simmer for 30 seconds and serve.
Brush the lamb with another thin layer of mustard. Then cut the lamb into 4 cutlets. Spoon the pea, pancetta and carrot mix into each dish.
Serve 4 lamb cutlets over each, then add some of the sauce to finish.
Add just a little crush of sea salt over each dish.