Prepare the hollandaise by whisking the Greek yogurt, one egg yolk, lemon juice, and Dijon mustard in a small heat-safe bowl.
Place the bowl over a pot of simmering water, ensuring the bottom of the bowl does not touch the water, and whisk constantly for 3-5 minutes until the sauce is thickened and warm.
Remove the sauce from heat and stir in the sea salt, black pepper, and cayenne pepper, then set aside in a warm spot.
In a separate non-stick skillet, lightly sear the Canadian bacon over medium heat for 1-2 minutes per side until heated through and slightly browned.
Toast the split whole grain English muffin until golden and crisp.
Fill a medium pot with water, add the white vinegar, and bring to a very gentle simmer.
Crack the remaining two eggs into individual small ramekins, then carefully slide them into the simmering water one at a time.
Poach the eggs for exactly 3 minutes until the whites are opaque and set, but the yolks remain soft and runny.
Assemble the dish by placing the Canadian bacon slices onto the toasted muffin halves, topping each with a poached egg, and drizzling generously with the warm yogurt hollandaise.