Wash the potatoes thoroughly, cover and cook in boiling water for about 15 minutes, drain, rinse with cold water, peel and rinse with cold water. Peel asparagus and cut off woody ends. Peel the carrots, leaving a little green.
Wash the rosemary, dab dry and, except for something to garnish, pluck needles from the stems and chop them. Wash lime hot, rub dry and cut into slices. Spread butter in flakes, lime, rosemary, asparagus and carrots on 4 sheets of parchment paper, season with salt and pepper, fold into packets and tie together with kitchen string.
Cook in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 25-30 minutes. Wash the fish, pat dry and divide into 4 portions. Heat 10 g clarified butter in a pan.
Fish in it on the skin side, depending upon thickness, 6-7 minutes roast, with salt and pepper season, turn and on the meat side 1-2 minutes to end roast. Heat 20 g clarified butter in a pan. Fry the potatoes for about 6 minutes, turning them until golden brown, season with salt and pepper.
Remove the parcels, arrange on plates with potatoes and fish and garnish with rosemary.