Put the salmon fillets into a shallow pan with the white wine and stock powder. Cover with a piece of buttered greaseproof paper or foil. Bring to the boil, reduce the heat and simmer for 3-4 minutes. Turn off the heat.
Meanwhile, cook the potatoes in gently boiling water for about 15 minutes, until tender. When they are almost done, lightly cook the samphire in boiling water for 2-3 minutes. Drain well and add the butter and watercress to the potatoes, then crush them lightly with a potato masher or fork.
Share the potatoes between 2 warm plates and place the salmon fillets on top. Reduce the salmon cooking liquid by boiling it rapidly for a few moments, then remove from the heat and stir in the double cream and chopped dill.
Serve the samphire with the salmon and potatoes, with the sauce spooned on top.
Notes
You can really taste the sea-salty flavours of the marshes where the samphire grows – so you won’t need to add salt to the recipe.