Prepare the Tuna: Open the tins of tuna and drain them thoroughly. I use the lid of the tin to press down firmly and squeeze out every last drop of water or oil. Transfer the drained tuna to a medium-sized bowl and use a fork to flake it into small pieces.

Add the Aromatics: Add the finely diced celery, red onion, and chopped fresh dill to the bowl with the tuna. The small dice is crucial for the final texture.

Create the Dressing: In a separate small bowl, whisk together the halal mayonnaise, Dijon mustard, fresh lemon juice, black pepper, and a small pinch of salt. Combining the dressing separately ensures everything is evenly distributed.

Combine Gently: Pour the mayonnaise mixture over the tuna and vegetables. Use a spatula or fork to gently fold everything together until just combined. Be careful not to overmix, as this can make the tuna mushy. You still want to see distinct flakes.

Taste and Rest: Give the mixture a taste and adjust the seasoning if needed. You might want a little more salt, pepper, or another squeeze of lemon. I find that letting the mixture sit in the fridge for 10-15 minutes allows the flavours to meld together beautifully.

Prepare the Bread: While the filling is resting, lightly butter one side of each slice of bread. If you like your sandwiches toasted, you can toast the bread in a toaster or a dry frying pan for 1-2 minutes per side until lightly golden.

Assemble the Sandwiches: Lay four slices of bread, buttered-side up, on your work surface. Place a few crisp lettuce leaves on top of each. Spoon a generous amount of the tuna and halal mayo filling over the lettuce, spreading it evenly.

Finish and Serve: If using, add a layer of sliced cucumber or tomato. Top with the remaining four slices of bread, buttered-side down. Press down gently, slice the sandwiches in half diagonally, and serve immediately.