Boil or poach chicken breasts in salted water for about 15 minutes until cooked through. Cool and shred.

Mix shredded chicken with mayonnaise, Dijon mustard, red bell pepper, green onions, lemon juice, salt, and pepper.

Slice cucumbers lengthwise into thin strips.

Place one tablespoon of chicken salad on each cucumber slice and roll tightly.

Refrigerate assembled roll-ups for at least 30 minutes before serving.