Lobster & Celery Rolls - Andrew Zimmern

Ingredients

• 1 small celery root, peeled and cut into 2 or 3 chunks
• Kosher salt
• 8 stalks celery, cut into 2- to 3-inch lengths
• 1 cup sugar
• 2 cups apple cider vinegar
• 4 brioche buns, split
• 3 to 4 tablespoons unsalted butter, softened
• 1 1/2 pounds cooked lobster knuckle meat, coarsely chopped
• 1/3 cup mayonnaise
• 2 teaspoons fresh lemon juice
• 1/3 cup chopped celery leaves
• 3 sprigs fresh tarragon, leaves chopped
• Freshly ground black pepper
• 1/4 cup fresh dill fronds
• Mustard oil or mustard caviar (pickled mustard seeds), for garnish
• Dill flowers, for garnish (optional)