Heat your oven to 200°C/Fan 180°C/Gas 6. Zest and juice the orange. Tip the flaked almonds into a pan. Dry fry for 2 mins, shaking the pan, till lightly toasted. Add one-third of the butter, half of the orange juice and all the raisins. Cook for 2 mins till the butter has melted. Tip into a bowl to cool.
Tip the flour into a bowl, saving 1 tbsp for later. Add the orange zest and remaining butter. Rub the flour and butter together with your fingertips to form fine breadcrumbs.
Separate the egg. Add the yolk to the flour mix (keep the white for later). Stir through with a fork till combined. Add 1-2 tbsp water to form a smooth, not too wet, dough.
Sprinkle the reserved flour on your work surface. Roll the pastry out as thinly as possible. Divide into two. Each piece should be large enough to drape over the salmon.
Place the salmon fillets skin-side down on a baking tray lined with baking paper. Top with the buttery almond and raisin mix. Drape the pastry over. Tuck the edges in close to the sides of the salmon, pressing firmly onto the salmon. Brush over the egg white and sprinkle with black pepper.
Slide the salmon into the oven and cook for 15 mins. The salmon should be cooked through and the pastry golden.
While the salmon is cooking, cut the carrots into quarters lengthways. Place in a pan and cover with boiling water. Simmer for 5 mins till tender when pierced with a knife. Drain. Pop back into the pan and cover with a lid to keep warm. Roughly chop the dill.
Toss the watercress with the remaining orange juice. Lift the salmon from the baking tray (the skin should stick to the paper). Serve on warm plates with the carrots and orangey watercress. Scatter over the chopped dill to garnish.