Preheat the grill on
its highest setting. Drain the tuna,
flake it into a bowl and mix with the
spring onions and mayonnaise.
Season with salt and plenty of
freshly ground black pepper.
Toast the bread
under the grill until it’s nicely
browned on both sides, then spread
the tuna mixture on top, right up to
the edges of the toast. Scatter over
the cheese and put back under the
grill until the cheese is bubbling.