Top tuna with cheese, packing it on generously, and slide sandwiches under broiler. Broil until cheese melts and bubbles, 4-5 minutes. Remove tuna melts from broiler and serve immediately.
Tip the tuna into a bowl with the spring onion, red onion and cheddar. Use a fork to flake apart the tuna and mix everything together. Add the mayonnaise, lemon juice, lots of pepper and a little ...