Fill a 12-inch skillet nearly to the rim with water. Add the vinegar, 1 teaspoon of salt and bring to a gentle simmer over medium heat.
While water comes to a simmer cook the bacon in a 12-inch fry pan over medium heat until well-browned on each side. Transfer to a paper towel-lined plate and cover with foil to keep warm.
When water comes to a simmer crack an egg into a cup and carefully slide it into the hot poaching liquid. Quickly repeat with remaining eggs. Using a slotted spoon carefully corral the white of each egg around its yolk. Poach the eggs, turning them occasionally with a slotted spoon, until the whites are firm or to the desired degree of doneness, 3 to 5 minutes. Using a slotted spoon, remove the eggs and transfer to a kitchen towel. Lightly dab the eggs with the towel to remove any excess water.
While eggs are poaching blend the egg yolks and lemon juice together in a blender until smooth and frothy, about 10 seconds. With the blender running, very slowly drizzle in half the butter until the mixture is quite thick, about 1 1/2 minutes. Blend in 2 teaspoons of hot water. Continue to slowly blend in the remaining butter, about 1 minute. Blend in additional hot water, 1 teaspoon at a time, as needed until the sauce coats the back of a spoon. Stir in the cayenne pepper and season with salt and pepper to taste.
Arrange the English muffins on individual plates and top with bacon. When the eggs are cooked, place them on top of the bacon, pour the hollandaise sauce over the eggs and garnish with the chives.