Spread a layer of mayo on one slice of bread. Stack with grilled zucchini, red pepper, and a handful of fresh arugula. Sprinkle the sesame seeds on top. Close with the second slice of bread, pressing gently to hold it all together.

Heat a medium non-stick pan over medium-high heat. Lightly butter the outside of the sandwich, then grill for 2-3 minutes per side until the bread turns golden brown and crisp. Remove from heat and let it cool.

Slice the cooled sandwich in half and pack it in a hard lunch container. For added freshness, keep any sides like fruit, veggie sticks, or chips in a separate compartment or container. Use an ice pack, if necessary.