Crack the eggs into separate ramekins or small glass dishes and set aside.
Fill a medium saucepan two-thirds full with water and bring to a moderate rolling boil. Add white vinegar. Using a spoon, quickly swirl the water around forming a funnel, then gently add one egg. Cook for three minutes, then remove using a slotted spoon and carefully set aside on a soft surface. Repeat with remaining eggs.
Prepare Hollandaise Sauce:
Add the egg yolks, lemon, and cayenne pepper to a food processor or blender. Cover and blend on medium until well combined, about 1 min.
Turn food processor to high and slowly drizzle in the hot melted butter through the opening in the lid. Continue to blend until thickened. Taste for seasoning and adjust as needed; mix again to blend.
Transfer sauce to a serving bowl and set the bowl in a hot water bath to keep warm until ready to serve.
Toast the roll halves and assemble: Place one piece of cheese on each roll and top with two slices of Canadian bacon, a poached egg, and prepared Hollandaise sauce. Season with additional salt and pepper, to taste.