Set the bowl over the saucepan, making sure the bottom of the bowl does not touch the water.
Heat, whisking constantly, until the mixture turns pale yellow, thickens slightly and increases in volume.
Remove the bowl from the heat.
Pour in the melted butter in a thin stream, a little at a time, whisking constantly, until the sauce is smooth and thick.
Keep the sauce warm while you cook the eggs.
Poached Eggs
Fill a saucepan with about 8 cm of water.
Add the vinegar.
1 dash vinegar
Heat until the water is gently simmering.
Crack a cold egg into a small cup or saucer.
8 eggs,
Hold the cup just above the simmering water.
Gently slide the egg into the water.
Repeat with the remaining eggs.
Cook in barely simmering water for 3 to 5 minutes, until the whites are set and the yolks are cooked to your liking: 3 minutes for a runny yolk with large eggs.
Lift out the eggs with a slotted spoon.
Drain them thoroughly on paper towels.
Muffins and Bacon
While the eggs are cooking, split the English muffins in half.
4 English muffins
Toast the muffin halves.
Assembly
Place the 8 toasted muffin halves on the plates, cut side up.
Top each half with a slice of back bacon.
8 slices lean back bacon
Place a poached egg on the bacon.
Spoon about 2 tablespoons of hollandaise sauce over each egg.
Serve immediately.
Notes
Canadian bacon and English muffins in Europe: Canadian bacon is lean pork loin, cured and sometimes smoked, cut into round slices; British “back bacon” is the same cut. You can replace it with cooked ham sliced 3 to 5 mm thick. In this recipe the bacon goes on the muffin as is; you can also sear it briefly in a frying pan over medium-low heat, just long enough to warm it through and lightly brown the edges. If you don't have English muffins, Toastbrötchen (in Germany) or toasted brioche rolls make a good base. The recipe uses whole wheat muffins, but plain muffins work too.Amount of sauce: the recipe makes about 240 ml of hollandaise, or 2 tablespoons for each of the 8 eggs. For lighter plates, spoon on a little less sauce.Broken sauce: hollandaise can break if it is overwhisked or if the butter is poured in too quickly. There are two ways to rescue it: whisk a fresh egg yolk in a small bowl, then gradually whisk in the broken sauce; or put 1 tablespoon of water in a small bowl and add the broken sauce a little at a time, whisking vigorously, until it is smooth again.Microwave hollandaise (variation): in a 1-liter glass measuring cup, whisk together the yolks, lemon juice, cayenne pepper and salt. Gradually whisk in the melted butter. Microwave on medium power (50%) for 45 seconds to 1 minute, until the sauce thickens, whisking after 30 seconds and again at the end.Storing and freezing hollandaise: the sauce freezes well. Thaw it in the refrigerator, then reheat it in a double boiler over hot but not boiling water, stirring constantly. If it breaks, rescue it as described above. To keep it warm while serving, you can pour it into a thermos preheated with boiling water.Poaching ahead: for a stress-free brunch for 4, poach the eggs up to two days ahead, no more than 4 at a time so you don't overcrowd the pan, cooking them for only 90 to 100 seconds. Plunge them straight into a bowl of ice water, then keep them in the cold water in the refrigerator. When you're ready to serve, return them to simmering water for 30 to 60 seconds to reheat, then blot them on paper towels before placing them on the muffins. With 8 eggs, also poach them in two batches if your saucepan is small.