Slice the flank steak into thin strips against the grain to ensure tenderness.
Finely dice the red bell pepper and red onion.
Heat the avocado oil in a large skillet over medium-high heat until shimmering.
Add the steak strips to the skillet and season with sea salt, black pepper, chili powder, and garlic powder.
Sear the steak for 3-4 minutes until browned and cooked through, then transfer to a plate.
In the same skillet, add the diced peppers and onions, sautéing for 3 minutes until they begin to soften.
Add the black beans to the skillet and cook for another 2 minutes until heated through.
Warm the tortilla in a separate dry pan over medium heat for 30 seconds per side until pliable.
Assemble the burrito by placing the steak, bean mixture, Greek yogurt, salsa verde, and cilantro in the center of the tortilla.
Fold the sides of the tortilla inward and roll tightly from the bottom up to serve.