How to Make It
Preheat grill to medium-high (400°F to 450°F). Place onion on oiled grates. Grill, turning 90° occasionally, until charred, 4 to 5 minutes. (Keep concentric rings intact.) Turn and repeat. Transfer to a bowl; cover with plastic wrap. Let stand 10 minutes.
Combine beans, rice, oats, olive oil, and jerk seasoning in a food processor. Pulse, in batches, until mixture comes together. Form into 6 (½-inch-thick) patties.
Add canola oil to a shallow dish. Place 3 burgers at a time in dish; turn to coat both sides with oil.
Place burgers on grill, and grill, uncovered, until browned, about 4 minutes; turn. Top each patty with 1 cheese slice. Divide onions and pepperoncini among burgers. Top with remaining cheese slices. Grill, covered, until cheese melts, about 2 minutes.
Combine mayonnaise and Tajín. Spread mixture on bottom and top halves of buns. Place a black bean burger on each bottom bun; top with plantain chips, a few dashes of hot sauce, and top halves of buns.