This recipe is written for 4 servings but can easily be sized up for more servings. The hollandaise sauce recipe is enough for 4 to 5 servings.
Prepare all the ingredients necessary first: unpackage the smoked salmon, slice avocado, chop fresh dill and prepare the garnishes.
Prepare the Hollandaise sauce next. Fill a saucepan with a bit of water, low enough that mixing bowl will not touch the surface of the water. Bring the water to a low simmer. In the glass mixing bowl, whisk together the egg yolks, lemon juice, a pinch of salt and freshly ground black pepper. Whisk vigorously until thick and pale. Place the bowl over simmering water. Whisking constantly, slowing begin pouring in the melted butter, a tablespoon at a time; this process will take a few minutes.
Continue cooking and whisking the sauce until it thickens to desired consistency. Remove the sauce from heat, cover with plastic wrap and keep warm.
Preheat a large frying pan and melted 1 tablespoon of butter (or, use olive oil). Once the butter is melted, add the English muffins and toast on both sides. Alternatively, brush the muffins with melted butter, then place onto a baking sheet and toast in the oven under the broiler for a couple minutes.
Poach the eggs last. Bring a saucepan of water to low simmer and add the vinegar and season the water with salt. Break one egg at a time into a small ramekin. Swirl the simmering water in one direction, then drop the egg into the center. If saucepan is large enough, cook multiple eggs at a time. Eggs will cook for 1 1/2 to 3 minutes. Test the egg for doneness by lifting it out of the water with a slotted spoon - the egg white should be firm but egg yolk still soft. Set the done eggs onto a paper-towel lined plate to absorb any excess water.
To assemble the sandwich, first layer the English muffin with sliced avocado, top with smoked salmon, follow with poached egg and generous amount of Hollandaise. Garnish top with fresh dill and capers. If Hollandaise sauce has become too thick, thin the sauce with a tablespoon of hot water and whisk. Serve immediately!