Drain and rinse the black beans, then pat them completely dry with a paper towel to ensure the burgers aren't mushy.
In a medium bowl, mash the black beans with a fork until mostly smooth but with some whole beans remaining for texture.
Finely dice the red bell pepper and mince the garlic clove.
Add the oats, egg, 0.25 cup of the Greek yogurt, nutritional yeast, diced pepper, garlic, cumin, sea salt, and black pepper to the mashed beans.
Stir the mixture until well combined and let it sit for 5 minutes to allow the oats to hydrate and bind the ingredients.
Form the mixture into two thick patties.
Heat the olive oil in a non-stick skillet over medium heat and cook the patties for 4-5 minutes per side until a golden-brown crust forms.
While the burgers cook, prepare the crema by mashing the avocado with the remaining 0.25 cup of Greek yogurt and lime juice until smooth.
Serve the hot patties topped with a generous dollop of the avocado crema.