Drain and rinse 220 g canned black beans thoroughly.

Thinly slice 1 large onion on a cutting board.

Heat 1 tablespoon cooking oil in the frying pan over medium heat.

Cook the sliced onion, stirring occasionally, until brown and caramelized, about 15 to 20 minutes.

Stir a pinch of granulated sugar into the onion during cooking if desired.

Mash the drained black beans with a fork in a mixing bowl until chunky.

Add 1 teaspoon ground cumin, 1/2 teaspoon smoked paprika, and 1 teaspoon dried oregano to the mashed beans.

Mix in 2 tablespoons soy sauce and 5 tablespoons breadcrumbs until a moldable mixture forms.

Add up to 4 tablespoons water if the patty mixture is too dry, then mix again.

Refrigerate the bean mixture while preparing the burger sauce.

Combine 6 tablespoons vegan mayo, 2 tablespoons ketchup, and 1 teaspoon mustard in the second mixing bowl.

Stir in 1 teaspoon chopped pickles and salt to taste until the sauce is smooth.

Divide the chilled bean mixture into 3 equal portions.

Shape each portion into a large, compact burger patty.

Heat the remaining 1 tablespoon cooking oil in the frying pan over medium heat.

Fry the 3 bean patties until golden brown on both sides, about 4 to 5 minutes per side.

Spread the prepared sauce onto the 3 vegan burger buns.

Assemble each bun with 1 bean patty and an equal portion of caramelized onions.