Add chicken pieces to a saucepan of cold water. Put a thermometer into the thickest part of a chicken piece.
2 chicken breasts
Bring to a boil.
Cover and turn off the heat. Remove from the pan when the temperature reaches 150 degrees. This typically takes about 15 minutes after the water starts to boil.
Remove the chicken when it is done, and allow to cool for 5 minutes.
Combine the mayonnaise, celery, onion, green onion, Dijon, dill, salt and pepper in a small bowl.
1/2 cup real mayonnaise, 1 stalk celery, 1 green onion, 1 tsp dijon mustard, 1 tsp salt, 1 tsp fresh dill, 1/2 tsp black pepper
Whisk it well to combine.
When the chicken is cool enough to handle, cut it into ½ inch cubes.
Fold the chicken into the dressing. Refrigerate for at least 1 hour or overnight for best results.
Lightly toast 8 slices of bread. Build the sandwich with Romain lettuce, topped with salted and peppered Roma tomato slices, then the chilled chicken salad.
8 slices white bread, 4 leaf romain lettuce, 3 roma tomatoes