I feel relaxed and comfortable as the madness of Christmas winds down, and I take great and patient pleasure in the careful construction of one of my food events of the year: the Boxing Day Sandwich. It is an embodiment of the very spirit of Christmas. All the stragglers, the leftovers and the overlooked, brought back together the day after Christmas, to make something truly delicious.

As this sandwich is made of leftovers, yours will no doubt be different, but please think of this as a guide, a general approach to the thing.

We go to the pub on Boxing Day as early as hangovers allow and I always buy an extra bag of pork scratchings – and some crisps – to take home and slap in my mega sarnie.

The only thing you can get wrong when it comes to this sandwich is not making it big enough. This should be the biggest sandwich of the year. By miles.

The bread

We make focaccia at the sarnie shop, but use anything you like. I think sourdough is much too chewy and the air-holes far too big to be any use in a decent sandwich, but each to their own. I suggest a tranche of focaccia 6cm high, 9cm wide and 14cm long.

The turkey

Chop up 150g of leftover turkey, put it in a pan, cover it in gravy, add a splash of water and set it aside.

Mayonnaise

Plonk two heaped tablespoons of mayo into a bowl, add 2 flat tablespoons of leftover gravy and 1 teaspoon of your favourite condiment. Anything, mustard, cranberry, horseradish. Stir it until completely integrated, set aside.

Add some crunch

Hopefully you’ll have leftover raw sprouts (5 or 6), carrots (1-1½ will do), some kind of lettuce (½ a baby gem) and a load of parsley (a big handful). Whatever you’ve got, go really thin (ie veg peeler) or grated on harder stuff and don’t be too tough on the softer stuff (rip, don’t cut). Put your veg in a bowl, and mix up a vinaigrette to put on it later: 1 tablespoon of acid (lemon juice or vinegar) to 2 tablespoons of oil (nice rapeseed or olive oil) and a “two finger one thumb” pinch of salt. Ideally, stick it all in a jam jar or something with a lid so you can shake it to emulsify.

Use up those vegetables

Take your leftover roasties, bread sauce, cooked veg and stuffing and mash them in a bowl with a fork. Add more pepper, more salt and a nice squeeze of lemon juice. A bit more of your condiment of choice if you so choose. Then crack an egg into it. Mash. Mash. Mash. Use your hands to squeeze them into little patties and get the egg properly incorporated. If you have the time, half an hour in the fridge will help them hold together when you fry them. Make them roughly half the size of your sandwich so the knife can go between them when you cut the sandwich in half later. And don’t make them too thin. You want soft inside, crunchy outside, post-frying.

Crisps (seriously)

Procure either (or perhaps both) a bag of pork scratchings or some ready salted from the pub. Give the scratchings a go with a wooden mallet or a rolling pin, still in the bag, to break them into little teeny chunks. If you’ve got crisps, open the bag and give them a few crushes with your hand.

Assemble the sandwich

Pour a large beverage of your choice. This is Boxing Day and all food should be accompanied by some kind of drink.

Ready the bread

Put your meat pan on the cooker on a medium-high heat.

Put your frying pan on with some goose fat or butter in it, again on a medium-high heat. Let the pan get nice and hot and slide your little bubble-esque patties in and turn the heat down to medium. Leave them be until you’re worried they’re burning a touch then they’ll be less likely to fall apart when you flip ’em over and get a nice tasty, crunchy, golden crust.

Smear your mayo all over the top layer of your bread. Cover every bit.

Shake your jar of vinaigrette like a mad person. Tip contents onto your raw veg salad and toss it all about.

Cover the bottom piece of bread in the hot meat, not too much liquid or the bread will break up.

Plonk the bubble-esque patties on top of that. Dressed veg/salad on top of that. Crisps on top of that (about half a pack).

Sprinkle the smashed-up scratchings all over the mayo (also about half the pack).

Lid on. Bit of a squish. Cut in half with your biggest sharpest knife right between the patties. Pour the leftover gravy from the pan into a warm, little flat bowl for dunking the sarnie in.

Top up your beverage. Sit in front of the telly. Close eyes and feel all Christmassy and glad to be alive.

Take another bite.

Max’s Sandwich Shop, 19 Crouch Hill, Stroud Green, London N4 4AP