In a large cast iron skillet, melt 2 tablespoons butter and olive oil, over medium heat. Stir in the onion and bell peppers. Cook for about 10 minutes, or until the veggies are tender. Remove from the heat and set aside.
Lay the flank steak out and with a sharp knife, carefully cut horizontally into it from top to bottom, keeping the knife level to butterfly the steak.
Unroll the steak so it lays flat and generously season the top with the Taco and Chili seasonings and rub in.
On one half of the steak, evenly spread the sour cream. On the other half, evenly spread the beans. Top the entire steak with the onion and fajitas and top with the green chiles.
Starting on the longest side, tightly roll the flank steak up. Tightly tie it with a piece of butcher’s at one end. Some of the stuffing may squeeze out which you can push back in or remove. Finishing tying the meat up using a half hitch or double knot down the meat. See video for example.
Season the outside of the meat with Kent’s Original seasoning, or salt and pepper.
Preheat the smoker to 250 degrees F. Add some cherry wood chunks and place the steak on the smoker and shut the lid. Cook for about 40 to 50 minutes, or until the internal temperature is 110 to 115 degrees F.
Open the lid and continue to cook over high heat, turning the steak on all sides, until the internal temperature is 125 degrees F. Remove from the smoker and let rest about 5 to 10 minutes. Cut the string off. Slice and serve.