Bring a pan of water to the simmer and add the juice of the lemon, the bay leaf and the peppercorns. Season the salmon fillets and cook in the simmering water for around 6 minutes. Once cooked, remove from the cooking water and dram on kitchen towel.
Cut the stalks from the chard, and wilt both stalks and leaves in a hot frying pan. Season and keep warm.
Boil the eggs for 5 minutes, then cool in iced water. Remove the shells and set aside.
Put the egg yolks, with the mustard and vinegar into a mixing bowl and whisk together. Then, slowly add the oil until the mixture is thick. Finish with the lemon balm. Check seasoning and set aside.