Filling: Fry the beef with a splash of oil on medium-high until browned. Add in finely chopped carrots and onions, bay leaves, star anise and pearl barley, stir in picked thyme leaves. Add in wine to deglaze, and once reduced add the stock. Add finely chopped pickled walnuts and a splash of brine. Cover and let cook for two hours, uncovered for an additional 40 minutes. Season to perfection and chill overnight.
Dough: Make the next day. Combine yeast, sugar and tepid water, leave for 10 minutes. Meanwhile rub butter and flour together until consistency is crumbly. Pour in yeast mixture, milk and sea salt. Mix with a spoon then knead with hands until smooth and silky. Roll into a log, divide into 20 even sized balls. Leave to proof until doubled in size.
Assembly: Preheat oven to 325F. Discard bay leaf and star anise. One by one, flatten balls and add a heaping, dessert spoon full of filling. Pull the sides of dough up and around the filling, pinch together to seal. Place sealed side down on baking sheet. Bake for 20 minutes.
Horseradish Sauce: Combine jarred horseradish, crème fraîche and white wine vinegar. Add fresh grated horseradish for garnish.