Ensaladilla Rusa Deviled Eggs

Ingredients

• 1 medium Yukon Gold potato, peeled and cut into 1/2-inch pieces
• 1 small carrot, cut into 1/4-inch dice
• 12 large hard-cooked eggs, peeled and halved lengthwise
• 1/4 cup plus 2 tablespoons mayonnaise
• 1 tablespoon chopped parsley, plus more for garnish
• 1 teaspoon sherry vinegar
• Salt
• 1 celery rib, finely diced
• 3 tablespoons minced white onion
• One 6-ounce can oil-packed tuna, drained and flaked