1. To make the salsa verde, blend the sherry vinegar, herbs, capers, garlic, mustard and olive oil using the Braun Multiquick and its chopper accessory.
2. For the fishcakes, peel the potatoes, cut them into evenly sized pieces and bring to the boil in salted water. Cook for 10-15 minutes until they are slightly firm. Drain well. While hot, mash with the lemon juice and chopped parsley.
3. Season the salmon fillet and grill on each side for 2-3 minutes until just firm and cooked through. When cool, break into large flakes. Fold the cooked salmon into the potato puree and season well.
4. Shape the mixture into 4 large, neat cakes. Coat in the flour, dip them into the beaten egg and then breadcrumbs. Chill for 30 minutes.
5. To cook, heat a shallow layer of oil in a wide frying pan. Fry the fishcakes for 4-5 minutes until brown, then flip over and fry the other side for 2-3 minutes. Serve with salsa verde.