Put three tablespoons of olive oil in a medium frying pan set over a medium heat and, once it’s hot, add the onion and a half-teaspoon of salt, and cook, stirring often, for 20 minutes, until quite reduced and frazzled.

Take off the heat.

Meanwhile, spoon a couple of tablespoons of the liquid (aquafaba) from the tin of beans into a small bowl or mug and set aside.

Drain and rinse the beans, tip into a large bowl and roughly mash; leave a few whole or in big chunks.

Stir in the breadcrumbs, garlic granules, onion granules, chipotle paste, mustard, ketchup and a half-teaspoon of salt, then use your hands to mix until well combined; if need be, add some or all of the reserved aquafaba.

Divide the bean mix evenly into four, roll each piece into a ball, then put them one by one between two sheets of baking paper and press out to roughly 10cm- to 12cm-wide patties (I tend to make mine a wee bit bigger than the burger buns).

To cook the patties, put two tablespoons of olive oil in a medium frying pan, then fry two of the burgers for about six minutes in total, turning them once halfway, or when the base is crisp and golden.

Remove and set aside, add another two tablespoons of oil, then repeat with the other two patties.

To serve, split and toast the buns, spread a generous dollop of mayo over the cut side of the bases and top with a leaf or two of iceberg lettuce.

Add a bean patty and a couple of thin slices of tomato, and finish with a quarter of the caramelised onions.

On with the lids and eat immediately.