Place the chorizo and garlic in a food processor and pulse until you’re left with small pieces of chorizo. Tip into a large bowl and add the black beans, quinoa, parsley, egg, ground almonds, cumin and smoked paprika. Season with salt and pepper and stir together until fully combined. Using damp hands, shape into four burgers and set aside on a plate or small tray lined with non-stick baking paper.
Heat the oil in a large frying pan set over a medium heat. Add the burgers and fry for 5 to 6 minutes on each side, until golden on the outside and cooked through.
Put the avocado in a mini blender with a squeeze of lemon juice and blitz until smooth.
Slather the base of each bun with the avocado. Top with a burger, a few slices of onion and the other half of the burger bun.