Place the chicken breasts in a pot and cover them with water. Add the bay leaf, peppercorns, and a pinch of salt.

Bring the water to a gentle simmer and cook for 12 to 15 minutes, or until the chicken is fully cooked through.

Remove the chicken from the pot and let it cool slightly. Cut it into small bite-sized pieces.

In a large mixing bowl, combine the chicken, celery, red onion, grapes, pecans, and fresh dill.

In a separate small bowl, whisk together the mayonnaise, mustard, lemon juice, salt, and black pepper until smooth.

Pour the dressing over the chicken mixture and stir gently until everything is evenly coated.

Cover and refrigerate for 1 hour before serving so the flavors can come together.

Serve chilled in sandwiches, wraps, lettuce cups, or on its own.