1. Place tongue in a six to eight quart pot and cover with water.
2. Add bay leaves, onion studded with the cloves, and salt, and bring to a boil.
3. Lower flame and cook on a continuous low boil for three to four hours, or longer if desired.
4. If tongue floats to the top, rotate every now and then so it’s submerged in the water.
5. Remove tongue from pot and cool on a plate.
6. Peel off skin while still very warm.
7. Place in fridge to cool and slice the next day (tongue can be frozen at this point).
8. Reserve some of the liquid to reheat the tongue in.
9. For sauce, combine all ingredients in a food processor and process until smooth.
10. Taste and adjust seasoning.
11. Refrigerate until use.
To serve: Place a few slices of tongue on a plate, drizzle with horseradish sauce and garnish with chopped chives or scallions, if desired.