01 - In a large bowl, mash the black beans with a fork or potato masher, aiming for a consistency with some remaining texture. Incorporate the finely chopped red onion, red bell pepper, minced garlic, large egg, panko breadcrumbs, Cajun seasoning, smoked paprika, salt, black pepper, and optional fresh cilantro. Mix thoroughly until all ingredients are well combined.
02 - Divide the black bean mixture into 18 equal portions. Shape each portion into a small patty, approximately 1.5 inches (4 cm) in diameter.
03 - Heat olive oil in a large nonstick skillet over medium heat. Cook the patties in batches for 3 to 4 minutes per side, or until they achieve a golden brown hue and are firm to the touch.
04 - Lightly toast the mini slider buns or baguette slices until they are lightly golden.
05 - To assemble each mini burger, spread a layer of spicy mayo on the bottom half of a toasted bun. Place a cooked black bean patty on top of the mayo. Layer with shredded lettuce, a thin slice of tomato, and a mini dill pickle slice. Cap with the top half of the bun.
06 - Serve the mini burger bites warm. Garnish with additional fresh cilantro, if desired.