Heat the oil in a large skillet over medium heat. Add the sweet potato, onion, poblano, 1/2 teaspoon sat, and 1/4 teaspoon pepper and cook, tossing occasionally, until tender, 10 to 12 minutes.

Meanwhile, heat broiler. Season the steak with 1/2 teaspoon salt and 1/4 teaspoon black pepper. Place on a broiler proof rimmed baking sheet and broil for 3-4 minutes per side for medium-rare. Let rest at least 5 minutes before slicing.

In a small bowl, combine the sour cream and chipotles. Fill the tortillas with the steak, vegetables, and chipotle sour cream.