Roast Chicken Salad Sandwiches

INGREDIENTS

• 1 tablespoon dijon mustard
• Kosher salt and freshly ground black pepper
• Kosher salt
• 1 tablespoon finely chopped fresh tarragon
• 3 tablespoons finely chopped fresh parsley
• 2 baguettes, split open
• 1 tablespoon fresh lemon juice
• 1/2 lemon
• Potato chips, for serving (optional)
• 3 sprigs parsley or tarragon
• 1/8 teaspoon cayenne pepper
• 1 medium shallot, finely chopped
• 3 tablespoons finely chopped fresh chives
• 2 stalks celery, diced, plus
• 2 tablespoons chopped leaves
• 2 large egg yolks
• 1 4-pound chicken
• 3/4 cup vegetable oil
• Fresh lemon juice, to taste