Make the Patties

Drain and rinse the beans in a strainer. Let sit to drain for about 5 minutes. Place in a blender or food processor and pulse 5 to 10 times until all beans are cut small ~ be careful not to over process the beans!

Add the beans, Gouda, panko, flour, egg, cayenne, and a generous pinch of salt and pepper to a large bowl. Thoroughly mix the ingredients together by hand and then form into 4 to 6 equal patties. Set aside.

Caramelize the Onions

Heat 1 tablespoon of olive oil over medium heat in a large frying pan or saucepan. When hot, add the onions and cook, stirring often, until caramelized ~ about 20 minutes. Add an additional tablespoon of olive oil as needed. NOTE: if the pan gets too hot and the onions are starting to burn along the edges, you can deglaze the pan with a couple tablespoons of water.

Cook the Patties

When the onions are halfway done cooking, melt 2 tablespoons of butter in a cast iron pan. When hot, add the patties, evenly spaced and working in batches, if necessary. Cook for 5 minutes and then flip. Cook for an additional 3 minutes then added the shredded Gruyere to the top. Cover and let cook and additional 2 to 3 minutes (NOTE: Gruyere has a high melt temperature, which is why shredding it helps. It’s okay if it doesn’t look fully melted, it is!).

Meanwhile, mash the avocados in a small bowl with the back of a spoon or fork. Add the lime juice and a pinch of salt and pepper and stir to combine. In a separate small bowl, add the mayonnaise. Add the sriracha in to taste and stir to combine.

On the top part of the bun, smear the smashed avocado across it and then add the sriracha mayonnaise. Place the burger on the bottom patty and top with caramelized onions. Place the top bun on top and smash down, if desired.

Serve immediately. Enjoy!