2 (14-oz) cans black beans, rinsed and drained, divided
3 tablespoons mayonnaise
1/3 cup plain dry bread crumbs
2 teaspoons ground cumin
1 teaspoon dried oregano, crumbled
1/4 teaspoon cayenne
1/4 cup finely chopped cilantro
3 tablespoons vegetable oil
4 soft hamburger buns
Accompaniments: sour cream; salsa; lettuce
Pulse 1 can beans in a food processor with mayonnaise, bread crumbs, cumin, oregano, and cayenne until a coarse purée forms. Transfer to a bowl and stir in cilantro and remaining can beans. Form mixture into 4 patties.
Heat oil in a 12-inch heavy skillet over medium-high heat until it shimmers. Cook burgers until outsides are crisp and lightly browned, turning once, about 5 minutes total. Serve on buns.