Preheat the oven to 400ºF.
Line a baking sheet with parchment paper.
Put the black beans in a large bowl and, using a potato masher, mash until blended, with some larger pieces of beans remaining.
Set aside.
In a large sauté pan over medium-high heat, heat the olive oil.
Add the bell pepper and onion.
Sauté until softened, about 7 minutes.
Add the garlic and cook for 1 minute, until fragrant.
Add the cumin, chili powder, and paprika and cook for an additional minute.
Remove from the heat and transfer to the bowl with the black beans.
Add the Worcestershire sauce, quinoa, panko, and eggs and season with salt and black pepper.
Mix to combine.
Divide the bean mixture into six 6-ounce portions and form them into patties and place on the prepared baking sheet.
Bake until the outside is crispy, about 20 minutes, flipping halfway through.
During the last 5 minutes of cooking, add a cheese slice to the top of each patty.
Meanwhile, make the special sauce: Combine the mayonnaise, ketchup, sriracha, pickles, Worcestershire sauce, and salt and pepper to taste in a small bowl.
Set aside.
To serve, spread some special sauce on the bottom and top of each toasted bun.
Place a black bean patty on the bottom bun.
Add tomato slices and arugula.
Cap with the bun top and serve.