Step 1

Place beef in a large saucepan with herbs, spices and vegetables. Cover with cold water, add vinegar and bring to the boil. Reduce heat to low, then cover and simmer for 3 hours, skimming surface occasionally, until meat is very tender.

Step 2

About 30 minutes before beef is done, make the bearnaise. Place vinegar, wine and eschalot in a pan over medium heat. Cook for 2-3 minutes or until reduced to 1 tablespoon. Strain into a heatproof bowl, then cool slightly. Add egg yolks, then set bowl over a pan of simmering water (don't let bowl touch water). Whisk until pale, then slowly whisk in butter, 1 tablespoon at a time, until mixture thickens. Remove bowl from heat, then stir in horseradish and tarragon. Season, then keep in a warm place until ready to serve.

Step 3

Drain beef, discarding liquid and vegetables. Thinly slice meat, then serve with baby vegetables (see related recipe) and sauce, scattered with mustard fruits and parsley.