Rinse the salmon fillets, pat them dry, and season with salt and pepper. Turn them in the flour and shake off any excess. Heat the olive oil and butter in a skillet and fry the salmon for about 5 minutes on each side on a medium heat. Lift from the skillet and keep warm. Cut the ham into fine strips and fry it in the oil. Deglaze the skillet with the fish stock and sidra and leave it to reduce by at least half. Place the salmon fillets on a preheated serving dish and pour over the sauce. Serve with small roasted Yukon Gold potatoes in their skins and thick-sliced broiled beefsteak tomatoes, accompanied by sidra or light wine.