Heat oil and 15g butter over high heat in a sauté pan large enough to hold both fillets. Place salmon in the pan and sear for about 1 1/2 minutes on each side. Transfer pan to oven and roast until cooked through, about 3 minutes. Remove from heat and brush with butter.
Meanwhile, melt 30g butter over low heat. Add cabbage and sauté over low heat for about 5 to 7 minutes. Add nuts, sultanas, and seasonings and toss to combine. Place salmon fillets on a bed of the sautéed cabbage mixture and top with Salmon Mousse.
Vegetable oil, for frying
155g salmon scraps
120ml double cream
Pinch Spanish paprika
Pinch black pepper
Heat about 2 ½-cm oil in a Dutch oven or large, heavy skillet (with at least 5-cm sides) to 180 degrees C.
Combine remaining ingredients in a food processor until smooth. Scoop out a couple balls of salmon mousse and fry until golden brown. Transfer to a kitchen towel-lined plate to drain before serving.