Peel and chop the onion. Reduce 5 tbsp. lemon juice, chicken stock and onions by half. Leave to cool.
In the meantime, wrap the medillons with bacon and tie them with kitchen string. Peel the asparagus and remove the ends. Melt butter in a small pot and remove from the stove.
Whisk the egg yolks and boiled stock over a hot water bath until it forms a rose. Remove the bowl from the water bath. Stir warm butter first drop by drop, then in a thin stream evenly into the foam.
Stir mustard and tarragon into the hollandaise sauce, season with salt and about 1 tbsp. lemon juice. Keep warm over the no longer hot water bath.
Bring 500 ml water with 2 pinches of salt, 1 pinch of sugar to the boil, cook the asparagus on a low heat for 10-12 minutes until firm to the bite. Drain and let drain.
In the meantime heat oil in a pan. Fry the meat on both sides, season with salt, pepper and paprika. Let the medallions fry on medium heat for 3-4 minutes on each side.
Arrange the medallions on the plate, add the asparagus and nap with the sauce.