In a blender, combine 1 egg yolk, 1 tablespoon melted unsalted butter, and 1 teaspoon lemon juice. Add a pinch of salt and pepper. Blend on high speed until smooth and creamy. Adjust seasoning if needed. Set aside.
Bring a small pot of water to a gentle simmer. Add 1 teaspoon of white vinegar to the water. Crack the egg into a small bowl. Create a whirlpool in the simmering water using a spoon, then gently slide the egg into the center of the whirlpool. Cook for about 3-4 minutes for a soft yolk. Remove the poached egg with a slotted spoon and place it on a paper towel to drain excess water.
Place the toasted English muffin halves on a plate. Top one half with 3-4 pieces of ButcherBox Cold Smoked Salmon. Carefully place the poached egg on top of the smoked salmon.
Drizzle the blender hollandaise sauce generously over the poached egg and smoked salmon.
Garnish with chopped fresh chives or parsley, if desired, for a pop of color and flavor. Serve immediately.