Pit the olives, drain the capers, and place them along with anchovies (if using) in a food processor. Pulse briefly for a coarse texture.

Split the bread horizontally. Drizzle olive oil on one half and spread harissa on the other.

Spoon the olive/caper mixture onto the oiled bread half. Spread the tuna evenly over the olive mixture.

Chop the preserved lemon and distribute it over the tuna.

Grind pepper and add salt. Close the sandwich and wrap tightly in plastic wrap. Refrigerate while preparing the couscous.

Wash and chop the parsley and mint. Cook the couscous according to package instructions.

Drain the cooked couscous. Add shallot, tomatoes, and the parsley-mint mixture. Add olive oil and salt. Mix well with clean hands.

Unwrap the sandwich and cut in half. Wrap in parchment paper and secure with tape. Place in a lunch pail.

Portion out the tabbouleh into a separate container and add to the lunch pail.

Optionally, slice some melon, wrap, and add to the lunch pail.