Desert Island burgers

I, in common with many people, would take a hamburger with me on the green mile. Well, that along with a roast chicken dinner; cauliflower cheese and chips; a chicken fajita and some sausages with a cloud of fluffy, creamy mashed potatoes (I'm gonna be on that desert island for a while anyway). I could go on, but why should I? I bought a meat mincer and it's time to christen it with some burgers.
And that's what I mean by my last request. I'm happy to make them with a big packet of beef mince if I'm making lots of small ones as a crowd pleaser, but for myself I want proper meat, chopped finely at home, handled as little as possible with a crunchy outside and a melting, bloody centre. I suppose you could get the crunchy coating with a packet of pasty pre-minced beef, but trying to cook that stuff rare makes for a hell of a spooky texture. Therefore, I take a basic but tasty cut of steak, for me a nice fatty sirloin, and mince it myself. I don't want an overworked paste but a loose pile of bubby beefy shreds. I then treat the beef as if it was a newborn puppy and shape it into a round- I like to use a basic burger press for this as it gives you less of a chance of making the proteins in the burger tighten.
Once I've shaped the burger it goes straight onto a screaming hot cast-iron skillet (you don't get the same crust from non-stick, but you do from stainless steel) and I season it right on the burning metal so the salt has no chance to break down the meat's delicate fibers. I also love a griddled burger, in which case it's probably okay to go non-stick, as griddles are made to take the heat. I flip it just once to keep as much juice in the burger as possible, and use the hot seared side to start melting the cheese and also absorb the caramelised onions I spread on top. I sometimes cook the onions myself, letting them colour very slowly in butter and a touch of sugar but I tend to just buy it snappily in a jar from the supermarket; equally, you can ignore my instructions to add the onion atop the burger whilst it cooks and just spread it on the bun as a relish, but I love the way the oniony sweetness suffuses the burger as it sears up and rests in its foil tent.
Don't let anyone tell you what sort of things you should want in your burger, this is no time to let others dictate your tastes. However, this is my blog, and I'll share what I want the burger to sit amongst in its sweet booty-ful bun in this recipe- chief of which is my special sauce. Similar to the kind of thing slathered on in a proper burger joint, but I use the far spicier English mustard rather than the sweeter American sort. I don't stray from shop bought mayonnaise and ketchup nonetheless, ever.

Serves 1, or 2 if each party is having just one burger
2 sirloin steaks, weighing 300-350g altogether
1 tbsp vegetable oil
Salt and ground black pepper
1 tbsp caramelised onions
2 slices American-style or Swiss cheese
1 tomato, cut into thick slices
Shredded lettuce

For the special sauce:
175g mayonnaise
3 cornichons or 1 large gherkin
2 tbsp tomato ketchup
2 tsp English mustard
1 tsp cider vinegar

Start by slicing the steaks into strips or chunks, and place them in a tray to go in the freezer. I use the tray I'll mince the meat into later to save washing up. Also, it's worth also chilling the mincer blades or the food processor blades. Chill all in the freezer for 20-30 minutes until the beef strips feel firmer.
While the steaks chill place your cast iron skillet into a warm oven to preheat, and make sure you remember that this makes the handle scalding too (I've burnt myself may times forgetting this). There's no need to do this if you're using a different sort of pan.
Make the special sauce by finely chopping the cornichons or gherkin, and combining with the other ingredients (the mayonnaise by the way, is give or take 3/4 measuring cup, which is easier than weighing the stuff). Taste, and add more vinegar if you want it sharper, ketchup for sweetness and mustard for extra poke. Special sauce making is a fluid kinda thing.
Also prepare a foil package for the burgers to rest on. Take two sheets of foil, layed one on top of the other onto a wooden surface (a steel one would chill it). If you're afraid the surface is too cold, use a pile of newspapers to insulate the foil. Today, I used the bubblewrap my new mincer came in.
When the meat has chilled start mincing it with the chilled blades. You can get a mincer attachment to a stand mixer, but an old-fashioned manual one does the job gratifyingly and equally well. Follow the instructions to mince it, and ensure you're using the coarse plate. If you have no mincer, use a food processor, though ensure you chop the meat in batches and do NOT let it become a mush. Line a burger press with some clingfilm, or the circles of greaseproof paper that come with the press and press the burger (and this mixture makes 2) gently into shape. Take it out and squish up the edges up a bit so the burger is thicker. If you are not using a burger press, you'll have to use oiled hands, and handle the meat as little as you can.
Set the preheated skillet on a high heat and heat up the oil. Or just whack any other sort of pan on a very high heat. Thwap the burgers onto the griddle or pan so the clingfilm or paper faces you and immediately remove the covering. Generously salt and pepper the exposed side and cook until a crust develops underneath- about 1-2 minutes. Flip again and season the second side. Spread the onions onto the two burgers, then lay the cheese on top of the onions. When the meat still feels squidgy and rare in the middle, transfer them to the foil package and wrap them up tightly. Allow to rest for 5 minutes.
Soak up the oils in the hot pan with the burger buns, and also grill the tomato slices on both sides in the oil and black bits the burgers left behind.
When the burger has rested, load it up onto the bun with tomatoes, lettuce, and plenty of the delicious special sauce. This is a basic, but perfect piling and what I go for most often, but feel free to play as much as you like. This is a deserted island, after all. I love this sandwiched between two big leaves of crunchy lettuce instead of the bun, for a throwback to the Atkins era, or topped with a fried egg and some snipped anchovies. To make a lady's brunch burger, as fabulous as it sounds, skip any vegetables (including the onions) and top the patty with a fried egg, crispy bacon and squish the whole lot together between a halved glazed doughnut. Heavenly.