Place the drained and rinsed black beans in a medium bowl and lightly mash with a fork or potato masher until mostly broken down but still some texture remains (leave about 25-30% whole for bite).

Sauté aromatics

In a small skillet over medium heat, warm 1 teaspoon olive oil and add the finely chopped onion. Cook, stirring, until translucent and slightly softened, about 4–5 minutes. Add the minced garlic and cook 30 seconds until fragrant. Remove from heat and let cool slightly.

Mix patty ingredients

To the mashed beans add the cooled onion and garlic, panko breadcrumbs, ground cumin, smoked paprika, chili powder, kosher salt, black pepper, lime juice, chopped cilantro (if using), and the egg. Mix thoroughly with a spoon or your hands until combined. The mixture should hold together when pressed; if too wet add up to 2 tablespoons more panko, if too dry add 1 tablespoon water or a little more lime juice.

Form patties

Divide the mixture into 2 equal portions and shape into patties about 3/4-inch thick and slightly wider than your buns. Place patties on a plate and chill in the refrigerator for at least 15 minutes to help them firm up (optional but recommended).

Cook patties

Heat a large nonstick skillet over medium heat and add remaining olive oil (about 1 tablespoon). When hot, place patties in the skillet and cook undisturbed 4–5 minutes until the bottom is browned and crisp. Carefully flip and cook another 3–4 minutes. In the last 1–2 minutes of cooking, place a slice of pepper jack cheese on each patty and cover the skillet briefly so cheese melts.

Avocado Aioli

In a small bowl, mash the half avocado until smooth. Stir in the mayonnaise, lime juice, minced garlic, salt, and black pepper. Whisk to combine. Add up to 1 teaspoon water if the aioli is too thick to spread. Taste and adjust salt or lime as needed. Refrigerate until ready to assemble.

Toppings & Assembly

Toast buns

Optional: Spread butter lightly on cut sides of the buns. Toast on a skillet or griddle over medium heat until golden, about 1–2 minutes per side. Remove from heat.

Assemble burgers

Spread about 1 to 2 tablespoons of avocado aioli on the bottom half of each bun. Place one lettuce leaf (or two small leaves) on the aioli, then set the hot black bean patty with melted pepper jack on top. Add 2–3 slices of tomato, then top with remaining lettuce if desired. Spread a little aioli on the top bun and close the burger. Serve immediately.

Serving suggestion

Serve the black bean burger with extra lime wedges, your choice of side (fries or salad), and any extra aioli on the side.