First make the Hollandaise sauce.
Put the vinegar in a small pan with the peppercorns and bay leaf. Reduce the vinegar over a high heat until there is only 1 tbsp left. Remove the peppercorns and the bay leaf.
Put the egg yolks in a food processor with the vinegar reduction. Gently melt the butter so that the butter solids fall to the bottom of the saucepan.
Turn the food processor on and slowly pour the butter on to the egg yolks with the motor still running. The sauce will start to thicken. When only the butter solids are left, stop.
If the sauce is too thick, add a little hot water.
Season to taste with salt and pepper and a little lemon juice.
Lightly toast the muffin halves on both sides.
Top each toasted muffin half with around 25g of salmon and set aside.
Fill a deep frying pan with water and add the vinegar.
Bring the water to the boil, reduce the heat to very low so that the water is simmering very gently.
Meanwhile, preheat the grill.
Crack each egg in turn into a ramekin, carefully slide the egg from the ramekin into the simmering water and poach each egg for 3 minutes only.
While the eggs are poaching heat the salmon-topped muffins for 1 minute under the hot grill. Gently remove the poached eggs from the water using a slotted spoon and dry on kitchen roll.
Top each muffin with a poached egg and then spoon a portion of Hollandaise sauce evenly over each egg.
Return the muffins to the grill and grill until the Hollandaise sauce is golden brown. Season with freshly ground pepper and serve at once.