Preheat your oven or toaster. Split the English muffins in half and lightly butter each half. Toast them until golden brown (about 3–4 minutes). Set aside.

Heat a medium saucepan with 2–3 inches of simmering water. Add the vinegar and keep at a gentle simmer.

In a small saucepan, melt butter until hot but not browned. In a separate heatproof mixing bowl, whisk the egg yolks, lemon juice, salt, and cayenne together.

Place the bowl over barely simmering water and whisk constantly until the mixture begins to thicken (about 2 minutes). Slowly pour in the hot melted butter, whisking continuously, until the hollandaise sauce is smooth and thickened.

In the same simmering water, crack eggs one at a time into a small bowl and gently slide into the water. Poach each egg for 3–4 minutes, until whites are set and yolks are still soft. Remove with a slotted spoon and drain.

In a skillet, cook the Canadian bacon over medium heat until just browned and heated through (about 2 minutes per side).

To assemble: Lay toasted muffin halves on plates. Top each with a slice of Canadian bacon. Place a poached egg on each, then spoon over the warm hollandaise sauce. Season with salt and pepper to taste.