Finely dice jalapeño and red onions. Portion half for cooking and half for topping omelet. To cooking portion, add diced mushrooms. To topping portion, add tomatoes and cilantro.
In small skillet, cook jalapeño, onion, and mushrooms until tender. Sprinkle in desired amount of beans and sprinkle with cumin and cayenne to taste. Remove to bowl and set aside.
In same skillet, melt a dab of butter and pour in beaten eggs. When almost set and able to get a spatula under, flip eggs and remove from heat. Top half with cooked vegetables and beans followed by shredded cheddar. Fold over and slide onto plate.
Top omelet with reserved tomato, onion, cilantro, jalapeño mixture, and avocado and a small dollop of sour cream if desired.
