To make the Hollandaise Sauce
Place the vinegar and egg yolks in a food processor with a pinch of salt. Blend until just combined. Gently heat the butter in a heavy-based pan until melted and just beginning to foam. Turn on the food processor and with the motor running at medium speed, pour in the melted butter in a thin, steady stream through the feeder tube. Continue to blitz for another 5 seconds and then pour back into the pan but do not return to the heat. Allow the heat from the pan to finish thickening the sauce as you stir it gently for another minute before serving. Season to taste with salt.
Meanwhile grill the rashers. While they are cooking poach the eggs.
Bring a saucepan of water to simmer, add the vinegar and salt. Break one egg onto a saucer, stir the water to create a whirlpool, tip in an egg. Repeat with a second egg. Leave to cook for 3 minutes. Using a slotted spoon, lift on to a plate and keep warm while cooking the remaining eggs. Keep the water hot.
Toast the bread and place on warmed plates. Divide the rashers between the plates. Place the eggs on top of the bread and spoon over the hollandaise sauce.