01 -
Slice your bagels in half and toast the outside under a medium grill until they're golden brown.
02 -
In a large bowl, combine your drained tuna, sweetcorn, chopped red onion, and mayonnaise until well mixed.
03 -
Divide the tuna mixture evenly between all the bagel halves, then top each with a generous sprinkle of grated mozzarella.
04 -
Pop them back under the grill until the cheese gets all melty and golden brown on top.