A fresh variation on the classic tuna melt, this open-faced sandwich can be made as mini melts for a party or potluck.

THE TARRAGON DRESSING: In a small mixing bowl, whisk together the ingredients until well combined.

THE SANDWICHES: Place the chicken and salt in a medium saucepan. Add cold water to cover. Bring the water to a boil. Immediately reduce the heat and simmer until the chicken is cooked through, about 8 to 10 minutes. Drain and cool for 5 minutes. Shred the chicken into bite-sized pieces and place in a large bowl. Chop the celery and add to the chicken along with the dressing. Stir to combine.

Lightly toast the bread. Heat the broiler (or toaster oven). Beginning with 4 toasted bread slices, top each with arugula leaves, one-quarter of the chicken mixture, tomato slices, 2 cheese slices, and a bread slice. Place the sandwiches on a baking sheet and broil until the cheese melts, about 4 minutes. Serve promptly.