Prepare the Mushrooms: Begin by removing the gills from the Portobello mushrooms and discarding them. Cut the mushrooms into smaller chunks. In a frying pan, sauté the mushrooms for a few minutes until the liquid they release is almost reduced.
Blend the Ingredients: In a large food processor, combine the cooked black beans and blend until they are mostly mashed. Add the sautéed mushrooms, minced cauliflower, chopped spring onions, minced garlic, vegan Worcestershire sauce, smoked paprika, salt, pepper, and nutritional yeast. Blend until you achieve a well-combined mixture.
Prepare the Mixture: Mix the flax meal with water and let it soak for 1-2 minutes until it forms a gel-like consistency. Add this flax mixture to the mushroom mixture. Also, mix in the bread crumbs or almond flour to help bind everything together. Blend until all the ingredients are fully incorporated.
Check the Texture: Test the texture by scooping up approximately ½ cup of the mushroom mixture and shaping it into a burger patty. If the mixture feels crumbly or like it might not hold together, add a bit more breadcrumbs or almond flour and mix again.
Shape and cook: Form the mushroom mixture into 6 burger patties. Preheat your air fryer according to its instructions.