Tuna Melt Toastie
What ruins most tuna melt toasties is water. Tinned tuna and mayo both release moisture as they heat up, and it soaks into the bread. To stop it, press the tuna properly dry, use far less mayo than you would for a cold sandwich (about 1 tbsp per 50g of tuna) and put a layer of cheese next to each slice of bread so the moisture has a barrier. Then cook it for 4 minutes.
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Recipe: Tuna melt toastie
Ingredients
- 2 slices medium-cut white or wholemeal bread
- 50g drained tinned tuna (about half a 145g tin, in spring water or brine)
- 1 tbsp mayonnaise (about 12g)
- 1 spring onion, finely sliced, or 1 tsp finely chopped red onion
- 1 tsp lemon juice
- 1 small pinch black pepper
- 40g mature cheddar, coarsely grated
- 10g salted butter, softened
Method
- Close the toastie maker and preheat it until the ready light comes on.
- Drain the tuna, then press it in a sieve with the back of a spoon until no more liquid comes out. It should look flaky and almost dry.
- Mix the tuna with the mayonnaise, spring onion, lemon juice and pepper. The mix should clump together and look moist but not wet.
- Butter one side of each slice. Put one slice buttered side down on the bottom plate.
- Scatter half the cheese on the bread, leaving a 1cm border.
- Spoon the tuna on top in a flat, even layer over the middle. Keep it slightly further from the edge than the cheese.
- Cover with the rest of the cheese and the second slice, buttered side up. Close the lid.
- Cook for 4 minutes in a standard machine or 5 in a deep fill. Rest for 1 minute before cutting.
Why this works: moisture control
A sealed toastie maker traps steam. That's good for melting cheese, but it's bad for wet fillings, because the steam has nowhere to go except into the bread. Tuna has three sources of water: the brine or oil in the tin, the water inside the fish itself and the mayo, which partly splits when heated.
Press, don't just drain
Tipping the tin over the sink still leaves a lot of liquid in the tuna. Pressing it in a sieve gets out much more. It's the most important step in the recipe.
Less mayo than a sandwich
A cold tuna sandwich takes plenty of mayo. A hot one doesn't need it, because the melted cheese takes over the job of binding the filling. About 1 tbsp of mayo to 50g of tuna (roughly 4:1 by weight) keeps it creamy without making the filling runny. Light mayo contains more water and splits more readily, so full-fat holds up better here.
Cheese as a barrier
Melted cheese is mostly fat, so it repels water. A layer of cheese against each slice of bread acts as a barrier between the tuna and the crumb. It's the same cheese-filling-cheese build we use for the ham and cheese toastie, done here to keep moisture out rather than to hold the layers together. For the best melters, see best cheese for toasties.
Tuna in oil or in water?
Tuna in oil tastes richer, but press it just as hard, because loose oil leaks out of the edges and smokes on the plates. Tuna in spring water is leaner and the more reliable choice. If you use oil-packed tuna, cut the mayo to 2 tsp.
Other appliances
In a frying pan, cook it on medium-low with a lid on for 3–4 minutes per side. An open pan lets steam escape, so it's more forgiving with damp fillings (see frying pan toastie). In an air fryer, cook at 180°C for 8–9 minutes, turning halfway. In a microwave toastie maker, use 35g of tuna and 30g of cheese and follow the timings in our microwave toastie maker guide.
Variations
- Tuna and sweetcorn melt: add 1 tbsp of sweetcorn, patted very dry on kitchen paper.
- Spicy tuna melt: stir 1/2 tsp of sriracha or a few chopped jalapeños into the mayo.
- Tuna, red onion and caper: use 1 tsp of chopped capers instead of the lemon. They add sharpness without adding water.
- Tuna and red leicester: it melts a little smoother than cheddar and gives the toastie a brighter colour.
- Curried tuna: add 1/4 tsp of mild curry powder to the mayo. It works on the same idea as our coronation chicken toastie.
Mistakes to avoid
- Using the tuna straight from the tin: the bread goes soggy and the toastie leaks.
- Adding tomato or cucumber: both add lots of water. Leave them for cold sandwiches, or see the drying technique in our cheese and tomato toastie.
- A thick mound in the middle: spread the tuna flat so the lid closes evenly and the middle heats through.
- Thin, cheap bread: it soaks up moisture fast. Medium-cut bread from a sandwich loaf holds up better. See best bread for toasties.
If the filling still escapes, read how to stop toasties leaking, or look at plates with deeper sealing edges in our best toastie maker guide.
FAQs
Is a tuna melt the same as a tuna toastie?
In the UK they're used for the same thing: tuna mayo with melted cheese, toasted. A US tuna melt is usually open-faced or pan-fried, while the UK toastie version is sealed in a sandwich toaster.
Can I make the tuna mix ahead?
Yes. Keep it covered in the fridge and use it within 24 hours. Give it a stir and, if any liquid has pooled at the bottom, dab it off before you build the toastie.
Why does my tuna toastie smell fishy in the machine afterwards?
Oil or brine has leaked onto the plates. Once the machine is unplugged and warm rather than hot, wipe the plates with a damp cloth and a drop of washing-up liquid. Our cleaning guide covers stubborn residue.