In a mixing bowl, combine sweet corn kernels, diced green bell pepper, diced tomato, crushed black pepper, dried oregano, and salt.

Gently toss the mixture to combine. Taste and adjust salt as needed.

Brush one side of each bread slice with melted butter.

On the non-buttered side of one bread slice, spread the sweet corn mixture evenly.

Top with grated mozzarella cheese.

Cover with another bread slice, buttered side up.

Grill the sandwich in a sandwich maker or grill pan until golden brown and crisp on both sides.

Repeat with remaining bread slices and filling.

Serve the grilled sandwiches immediately.