For the black bean burger: Combine the beans, cilantro, breadcrumbs, mayonnaise, cumin, salt, chipotle powder, oregano and black pepper in a bowl and mash with your hands until about 2/3 of the black beans are mashed. The mixture should hold together when you pat it into a burger. Shape 6 burgers from the mixture.
Heat a griddle over high heat, add the grapeseed oil and then the burgers. Cook until the burgers are seared on one side, 3 to 4 minutes. Flip and cook on the second side until browned, 2 to 3 minutes. Remove from the griddle and serve immediately following the plating instructions below.
To plate: Heat a griddle over high heat, add the grapeseed oil and then the pineapple slices. Cook until the pineapple slices are seared on one side, 2 to 3 minutes. Flip and cook on the second side until browned, 2 to 3 minutes.
Butter both sides of the burger buns and toast on the griddle until golden brown, 1 to 2 minutes.
Set the bottoms of the buns on 6 plates. Top each with a lettuce leaf, tomato slice, red onion slice and burger. Add the bun tops and serve each with a piece of seared pineapple and some vegetable chips on the side.