Tuna Sambal
Combine the tuna sambal, half the mayonnaise, chopped pickled capers or jalapeños, shallot and herbs in a small bowl. Taste and adjust the seasoning as you like. Add sliced fresh chillies too, if you’re feeling spicy.
Spread the remaining mayonnaise on all surfaces of the bread, then assemble the sandwich, beginning with two slices of cheese on the base, then the sambal tuna filling, followed by the remaining two slices of cheese. Top with the second slice of mayonnaised bread.
Heat a cast-iron skillet over medium heat, or use a sandwich press. Gently place the sandwich on the hot surface of the pan, then press down and cook until it has a crisp, golden surface and melty cheese inside. If you’re using a skillet, cook for about four minutes either side, carefully flipping in between, and make sure you keep pressing down on the sandwich as it cooks.
Transfer to a chopping board and sprinkle with a little flaky salt if you have it. Cut in half and eat immediately.
Tuna Sambal method
Place the shallots, chillies, garlic, tomato, white part of one lemongrass stalk and turmeric powder in a food processor or mortar and pestle and blend to a smooth paste.
Heat the oil to smoking point in a medium frying pan, then saute the lime leaves and sliced lemongrass over high heat until fragrant.
Add the onion and continue stir-frying until softened slightly, then add a couple of tablespoons of the sambal. Stir-fry for one to two minutes, then add the tuna.
Continue frying over medium-high heat until any liquid evaporates and the tuna begins to dry out somewhat in the pan. Break up any larger pieces of tuna as you continue to fry, then add the fish sauce and sugar. Taste at this point, add a little more sambal if you wish, and skip the salt if the tuna is already salty.
