You gain a lot in this dish by taking the eggs out of the refrigerator in good time so that they are at room temperature both for the sauce and the poached eggs.
Sauce Hollandaise
Melt the butter in a pan over low heat and let it cool slightly.
Use a clean pan to whisk the egg yolk, apple cider vinegar, lemon juice, and mustard over low heat.
Whisk longer and harder than you might expect. When it thickens a bit, slowly add the melted butter.
When the sauce is ready, season it with white pepper, cayenne pepper, and salt.
The sauce should be served immediately.
Bacon
Fry the bacon until crispy in a medium-hot pan without fat.
Poached Egg
Bring a pot of water to a boil, and crack each of the two eggs into its own small bowl/glass.
Add vinegar to the water and reduce the heat so the water just simmers.
Create a small whirlpool in the water with a spoon and drop one egg into it. Do the same with the other afterward.
Let it simmer for 3 minutes, then take it out and trim it so it looks nice.
Asparagus
Boil them for 1 minute, and they are ready to serve. Preferably in the water from the eggs.
Serving
Serve the poached egg with toasted bread (we used yesterday's hot wheat buns) and bacon. Pour the sauce on top and add, for example, thinly sliced asparagus and red onion.