Put the peas in a bowl and defrost. Quarter the peppers, clean and wash them. Cut the paprika quarters into strips. Wash, peel and slice the potatoes. Wash rosemary, shake dry and pluck the needles from 1 sprig.
Put the potatoes, herb butter, stock and rosemary in a saucepan, cover and simmer for about 10 minutes. Add peas and peppers after about 7 minutes. Wash the salmon pieces, dab dry and season with salt and pepper.
Heat the oil in 2 pans. Fry the salmon on both sides. Remove and place on a baking tray. Mix both mustards and breadcrumbs. Coat fish with mustard and grill under the hot grill for 3-4 minutes.
If there is still too much liquid in the pot with the vegetables, remove the lid and let it boil down for a few minutes. Season vegetables with pepper and possibly a little salt. Arrange the fish on the vegetables and garnish with rosemary.