Tuna Tramezzini

Put the tuna into a bowl and break it up very finely with a fork.

Add sour cream, mustard and lemon juice to the tuna and stir everything into a creamy mixture. Season with salt and pepper.

Peel the hard-boiled egg and slice it thinly. Slice the Fontina thinly as well.

Take the tramezzini slices out of the pack and spread one slice evenly with the tuna cream.

Place the egg slices and Fontina on top, cover with a second tramezzini slice and press lightly.

Cut the sandwiches into triangles and keep chilled until serving.