Prepare the quinoa according to the instructions on the package.
Finely chop or process the bell pepper in a food processor and put in a hot skillet. Spread evenly throughout the pan. Finely chop or process the onion, garlic, chili pepper and cilantro and add to the pan. Stir to combine with the bell pepper and cook for approximately 7 to 10 minutes, or until the vegetables release their water and they begin to dry out. You don't want wet and mushy vegetables in the burgers or they will fall apart and the texture will be mushy.
Put ¾ of the beans in a food processor and blend until they begin to form a ball. Put in a large mixing bowl with the whole beans. Transfer the vegetables to the bowl with the beans. Add the quinoa, breadcrumbs, spices and liquid smoke to the bowl.
Combine the tapioca starch and water and stir until it’s a thick and sticky consistency. Pour into the bowl with the beans, veggies, quinoa and breadcrumbs and stir well to combine. The texture should be thick and very sticky. Scoop out a ½ cup of the mixture, roll into a ball, then pat into a patty.
Heat large skillet on medium-high heat, add the oil and spread it evenly throughout the pan. Add the burgers (as many as will comfortably fit the pan, you may have to cook in batches) and cook for approximately 3 to 4 minutes or until they’re nicely browned. Use a spatula to gently flip and cook the other side for the same amount of time. For best results cover the burgers with a lid.
Put on a bun and top with the lettuce, tomato and avocado slices.