In a medium pot to medium-high heat, pour enough amount of water, the vinager, and some salt, and let it boil slowly.
Crack the eggs and place each one in separate small bowls.
Once the water is boiling, carefully pour one egg in it and let it cook for 3 minutes (the egg yolk must be runny when cutting the egg).
Carefully take it out of the water and place it on a plate with some kitchen paper.
Repeat this same step with the second egg. Set them aside until needed.
To assemble:
Spread some butter on the english muffin halves, and toast them on a pan to medium heat until they turn golden brown.
On the same pan, add some more butter and cook the ham on both sides.
To serve, place on a plate one of the toasted english muffin halves and the ham on top. Then place the poached egg and pour enough hollandaise sauce over it.