Sauté the Aromatics: Heat the olive oil in a large frying pan over a medium heat. Add the finely chopped onion and cook for 5-7 minutes, until softened and translucent. Add the minced garlic and finely chopped mushrooms and cook for another 8-10 minutes, until the mushrooms have released their liquid and it has evaporated. The mixture should be quite dry. Set aside to cool slightly.

Prepare the Beans: While the vegetables are cooking, place the rinsed and well-dried black beans in a large mixing bowl. Using a potato masher or a fork, roughly mash about half of the beans, leaving the other half whole for texture.

Combine the Patty Mixture: Add the cooled mushroom and onion mixture to the bowl with the black beans. Tip in the whole wheat breadcrumbs, beaten egg, smoked paprika, cumin, salt, and pepper.

Mix and Form: Using your hands or a sturdy spoon, mix everything together until well combined. The mixture should hold its shape when you squeeze it. Divide the mixture into four equal portions and shape them into patties about 2cm thick.

Chill the Patties: Place the formed patties on a plate lined with greaseproof paper and pop them in the fridge to chill for at least 15 minutes. I find this step is essential – it helps them firm up and prevents them from falling apart during cooking.

Cook the Burgers: Wipe out the frying pan you used earlier and add a little more olive oil. Place it over a medium heat. Carefully place the chilled patties in the pan and cook for 4-5 minutes on each side, until a deep golden-brown crust has formed and they are heated through. If using cheese, place a slice on top of each patty during the last minute of cooking and cover the pan with a lid to help it melt.

Assemble Your Burger: While the burgers are cooking, lightly toast the insides of your whole wheat buns. Mix the mayonnaise, ketchup, and Dijon mustard together to make a simple burger sauce. Spread the sauce on the buns, then layer with lettuce, the cooked veggie patty, a slice of tomato, and a few rings of red onion. Serve immediately.