You can use different types of bread!
In a bowl, mix tuna, Greek yogurt, 1.5T lemon juice, 1T allulose, sweet corn, and pepper.
On a sheet of plastic wrap, place heated and halved bread and pile the mixture onto one side.
Top with sliced onion, sliced cucumber, sliced boiled egg, and halved cherry tomatoes.
In a bowl, mix 0.5T whole grain mustard, 0.5T allulose, and 0.5T mayonnaise. Spread the sauce on the other slice of bread, cover, and wrap.