In a medium bowl whisk together warm vegetable broth, soy sauce, maple syrup, and 1 tablespoon neutral oil. Stir in the mashed black beans until mostly smooth with some small pieces for texture.

Sauté vegetables

Heat 1 teaspoon neutral oil in a small skillet over medium heat. Add finely chopped mushrooms and grated carrot and sauté 4–6 minutes until moisture has mostly evaporated and vegetables are soft. Season with a pinch of salt and remove to cool slightly.

Mix dry ingredients

In a large bowl combine vital wheat gluten, ground flaxseed, smoked paprika, onion powder, garlic powder, and black pepper. If using beet juice/powder for color, add it to the dry mix.

Combine and knead

Add the sautéed vegetables and the bean-broth mixture to the dry ingredients. Stir until everything comes together, then knead by hand in the bowl for 1–2 minutes until a cohesive, springy dough forms. If the mixture feels too dry add up to 2 tablespoons more warm broth; if too wet, add up to 2 tablespoons more vital wheat gluten.

Form patties

Divide the dough into 4 equal portions (about 145–160 g each). Shape each into a compact patty roughly 3/4-inch thick and 3.5–4 inches in diameter. Press a slight indentation into the center of each patty to help even cooking.

Rest

Let patties rest on a lightly oiled tray for 10 minutes to relax the gluten, which improves texture and helps them hold shape on the grill.

Grill & Finish

Preheat grill

Preheat a gas grill, charcoal grill, or grill pan to medium-high (about 375–425°F / 190–220°C). Oil the grates or grill pan with the neutral oil to prevent sticking.

Grill patties

Place patties on the preheated grill. Cook 4–5 minutes per side with the lid closed, brushing lightly with remaining 1 tablespoon oil or a little soy sauce during the first flip to encourage caramelization. Look for good char marks and an internal warm, springy texture. Total cook time ~9–12 minutes depending on heat and thickness.

Melt cheese (optional)

If using vegan cheese, place a slice on each patty during the last minute of grilling and close the lid to melt. Alternatively, toast buns on the grill 30–60 seconds cut-side down until lightly golden.

Season

After removing patties from the grill, sprinkle coarse salt and freshly ground black pepper evenly over each while still hot.

Burger Assembly & Toppings

Prepare sauce and buns

In a small bowl mix vegan mayonnaise, brown mustard, and ketchup to make a simple burger sauce. Split buns and lightly brush cut sides with olive oil; toast them on the grill or a skillet until golden-brown, about 30–60 seconds.

Assemble burgers

Spread a thin layer of sauce on both the top and bottom bun. On the bottom bun place a lettuce leaf, a grilled patty (with cheese if used), 2–3 pickle slices, a tomato slice, and some red onion rings. Top with additional sauce if desired, then cap with the top bun.

Serve

Serve immediately while patties are warm with extra pickles or fries on the side.