Season the chicken breasts with salt and pepper. Fry in butter for about 10 minutes. Remove, allow to cool and cut into thin strips.
Peel and finely grate the carrot. Rinse and cut the scallions into rings. Mix the chicken strips, scallions and carrot with the mayonnaise.
Separate the top of the bread box with a sharp knife. (Stale bread can be cut easier than fresh.) Cut the center of the bread box out with a 1 cm margin.
Remove the inner part of the bread. Cut into slices and toast. Spread with butter.
Spread the chicken mixture between two slices of bread and serve.