Tramezzini with Egg

If you are cooking the egg first: boil for 9–10 minutes until hard, then cool in cold water.

For a milder flavor, soak the chopped onion briefly in cold water and drain well.

A splash of water or a little milk will make the spread easier to spread if needed.

Let it rest in the refrigerator — the filling will firm up and spread more cleanly.

Use a sharp knife or bread knife and wipe it briefly between cuts so the edges stay neat.