Sprinkle each salmon fillet with 1/2 tsp salt and set aside for 20 mins (this helps draw out excess water and firm up the fillets). Rinse with cold water and pat dry with kitchen paper.

Heat the air fryer to 180C. Cut two 30cm circles of baking parchment and put a salmon fillet in the centre of each disc. Cut 2 lemon slices and place one on each fillet, then drizzle with oil or top with the butter. Lift the edges of the paper to the centre, then crimp together tightly to enclose the salmon. Cook for 10 mins.

Meanwhile, stir together the crème fraîche, mayonnaise and chopped dill. Season and add a squeeze of lemon juice to taste.

Carefully open the salmon parcels and scatter over the reserved dill fronds. Serve the salmon alongside the dill crème fraîche.