1 Wash and drain the watercress, plunge it 3 minutes in a pot of boiling salted water. Refresh it and drain it. Then, mix it finely and pass it through a sieve. Cover and set aside
2 Cut the butter into pieces, place them in a saucepan and melt them over low heat. Skim it
3 Put the egg yolks and 2 tablespoons of water in a frying pan. Place it on low heat and whisk in eights until the sabayon increases in volume, foams and becomes creamy. Remove from the heat, add salt and pepper and pour in the lemon juice.
4 Gradually pour the butter into the sabayon, whisking. Stir in the watercress. Keep warm on a very low heat.
5 Cut the salmon into fillets. Bring to the boil, 75 cl of water with coarse salt and sugar, in a saucepan. Dip the salmon needles in the water for 2/3 minutes. Drain them and serve them immediately with the watercress hollandaise sauce and rice (for example).