01 - Combine cooked chicken, celery, red onion, mayonnaise, Dijon mustard, fresh dill, parsley, and lemon juice in a mixing bowl. Season generously with salt and black pepper. Mix thoroughly until all ingredients are evenly distributed and the mixture holds together well.
02 - Using a vegetable peeler or mandoline, slice cucumbers lengthwise into thin, wide ribbons. Discard the initial slice consisting primarily of skin. Continue slicing to create flexible ribbons that can roll without breaking but are substantial enough to hold the filling.
03 - Pat cucumber ribbons thoroughly with paper towels to remove excess surface moisture. This step prevents the filling from becoming watery and helps the roll ups maintain their structure.
04 - Lay a cucumber ribbon flat on a clean work surface. Spread approximately 1 tablespoon of chicken salad mixture along one short end of the ribbon. If desired, place a baby spinach leaf on top of the chicken salad before rolling.
05 - Gently roll the cucumber ribbon around the filling, creating a tight cylinder. Place each completed roll seam side down on a serving platter. Continue until all ribbons and filling are used.
06 - Refrigerate the assembled roll ups for at least 10 minutes before serving. This chilling period allows flavors to meld and helps the rolls maintain their shape when handled.