Salt the sardines and fry them in a pan, skin side down, on medium heat for about 3-4 minutes, depending on size. Turn around if necessary until fully cooked.
Blanch the Savoy cabbage and green peas and reserve.
Heat a knob of butter in a pan, add the chopped leeks and fry on low heat until soft. Add the Savoy cabbage and green peas and continue cooking for 1-2 minutes. Finally, add the cream and bring to a gentle boil. Season with salt and pepper.
To serve, place the creamed greens on two plates, add 3 sardines on each plate and a few springs of fresh dill.