Preheat the Oven: Start by preheating your oven to 375°F (190°C). Line a large baking sheet with parchment paper to prevent sticking and make cleanup effortless.
Prepare the Mixture: In a food processor, combine the black beans, sliced mushrooms, walnuts, chopped red onion, oats, minced garlic, Dijon mustard, salt, liquid smoke, black pepper, and a pinch of cayenne. Pulse the ingredients until they form a well-combined but slightly chunky mixture. Avoid over-blending to maintain texture.
Shape the Patties: Scoop out about ¼ cup of the mixture for each patty and gently form it into a small, round shape using your hands. Repeat until you have 12 evenly sized patties. Place each patty on the prepared baking sheet, leaving some space between them.
Bake the Patties: Transfer the baking sheet to the preheated oven. Bake the patties for 25 minutes, flipping them halfway through the cooking time. This ensures even baking and gives the patties a slightly crispy, golden exterior while keeping the inside soft and flavorful.
Assemble the Sliders: Take the patties out of the oven and allow them to cool for a few minutes to ensure easier handling and assembly. Place each patty onto a slider bun and add your favorite toppings. Popular choices include lettuce, sliced tomato, onion rings, pickles, and a dollop of vegan mayo. Feel free to customize with your preferred sauces and extras.
Serve and Enjoy: Arrange the assembled sliders on a platter and serve them warm. Pair with sides like sweet potato fries, coleslaw, or a fresh green salad for a complete meal. These sliders are best enjoyed fresh, but leftovers can be stored and reheated for later.