Preheat oven to 350°F (175°C). Spread drained black beans in a single layer on a parchment-lined baking sheet and roast for 15 to 20 minutes until the skins begin to crack and beans are dry to the touch.

In a large skillet, heat 1 tablespoon of olive oil over medium-high heat. Sauté the onion, poblano pepper, and mushrooms for 8 to 10 minutes until the vegetables are softened and all moisture released by the mushrooms has evaporated.

Add the minced garlic to the skillet and cook for 60 seconds until fragrant. Remove the skillet from heat and allow the mixture to cool for 5 minutes.

In a food processor, combine the roasted black beans, sautéed vegetable mixture, chopped walnuts, panko breadcrumbs, egg, soy sauce, and spices.

Pulse the mixture approximately 10 to 12 times until the ingredients are thoroughly incorporated but still retain a chunky, textured consistency. Do not over-process into a smooth paste.

Divide the mixture into 6 equal portions (approximately 1/2 cup each) and shape into patties 1 inch thick. For optimal structural integrity, refrigerate the patties for 30 minutes prior to cooking.

Heat the remaining 1 tablespoon of olive oil in a cast-iron skillet or non-stick pan over medium heat.

Place patties in the pan and cook for 4 to 5 minutes per side until a deep brown crust has formed and the center is heated through.

Serve immediately on toasted buns with preferred condiments.