Gently melt the butter in a small pan for about 1 or 2 minutes.
Whisk the 4 egg yolks together with the lemon juice until the mixture is thick and doubled in size in a medium sized bowl.
Place the bowl over a pot of simmering water and whisk again. Don’t let the eggs get hot as they will scramble. Pour in the melted butter and continue to whisk.
Season with salt and pepper. Set aside.
Next you will need to poach your eggs. Pour water into a non stick pan so that it covers the bottom. Add in the vinegar and stir continuously. Slowly add in the eggs, 2 at a time depending in the size of your pan, and cook for 5 minutes.
Remove and set aside. Toast your muffins before layering on 2 slices of salmon. Top with a poached egg and drizzle a little hollandaise sauce over it. Season with gound black pepper.