1 (2 1/2-pound) beef rump roast, trimmed of all fat and silverskin
1 large celery root
1/2 pound carrots
1 bunch fresh, flat-leaf parsley, washed
1 large onion, cut roughly into eighths
2 fresh bay leaves
4 sprigs fresh thyme
1 tablespoon black peppercorns
4 small, dried chilies
Crusty, country-style, white bread, cut into thin slices, for serving
Coarse salt, to taste
Mustard, either Dijon-style or whole-grain, for serving
Horseradish, freshly grated or prepared, for serving
Good-quality olive oil, for serving (optional)
Using a length of kitchen twine, tightly wrap the roast, tying it 4 times around lengthwise and once around widthwise and leaving 2 long ends loose on either side. Holding ends together, suspend roast inside an 8-quart soup pot, measuring so that roast is about 1 inch from bottom of pot. Tie ends in a loop around a wooden spoon long enough to bridge top of pot. On outside of pot, using a marker or a piece of tape, mark point at which top of roast sits. Put tied roast on a plate and allow it to come to room temperature.
Meanwhile, halve the leeks lengthwise and wash them to remove all dirt. Trim leeks, reserving green trimmings to make stock (place them in pot). Trim the white parts into sticks no thicker than 1/2 inch wide and 2 1/2 inches long.
Peel the celery root and slice it into sticks about 1/4 inch by 1/4 inch by 2 1/2 inches. Save trimmings and add them to pot with leek trimmings. Peel carrots and slice into sticks sized similarly to celery root. Add trimmings to pot.
Stem the parsley and finely chop leaves. Add stems to pot along with the onion, bay leaves, thyme, peppercorns and chilies. Cover with 6 quarts water and place pot over high heat. As soon as water comes to a boil, reduce heat to a low simmer. Simmer gently, uncovered, for 45 minutes.
Meanwhile, assemble the bread, coarse salt, mustard, chopped parsley and horseradish and arrange on a platter.
After 45 minutes, strain broth through a large strainer, discarding vegetable scraps and reserving hot broth. Return broth to same pot, add 2 tablespoons salt and bring to a rolling boil.
One at a time, blanch carrots, celery root and leeks in broth until crisp-tender, for about 2 minutes after broth has returned to a full boil. Remove with a slotted spoon, drain and add vegetables to platter.
Return broth to a simmer, adding additional water if necessary to make sure liquid level reaches mark you made previously. Lower room-temperature roast into liquid, then bring broth back to a simmer. Cook roast to desired doneness, about 25 minutes for rare (a thermometer inserted should read about 120 F).
Remove roast from liquid and allow it to rest for 10 minutes on a cutting board. Slice roast into very thin slices. Arrange slices on platter, alongside blanched vegetables, condiments and bread. If desired, drizzle a little bit of the olive oil over vegetables. Serve immediately.
Makes 6 servings.