Classic Viennese Tafelspitz

For the beef and broth, rinse soup bones and boil in salted water, skimming foam as necessary. Rinse and trim leeks, cut in half lengthwise and cut into pieces about 3 cm (approximately 1 inch) long. Cut carrots with a crinkle cutter into thin ridged slices. Cut celery root into small cubes. Peel onion and cut into strips. Rinse beef and add to broth with vegetables, bay leaf and onion. Add enough water to pot to cover all. Bring to a boil, reduce heat and simmer 1 1/2 to 2 hours.

For the apple horseradish, peel, quarter and core apples and grate finely. Peel horseradish and grate finely. Mix apples, horseradish, oil, mustard and vinegar and add sugar to taste.

Remove tafelspitz from heat, skim fat and let stand briefly. For the gravy, strain about 500 ml broth from pan. Melt butter, dust with flour, sauté briefly and deglaze pan with the broth. Simmer gravy about 2 minutes, whisking vigorously. Stir cream and chives into gravy and season with salt and pepper.