Add wood chunks, chips or pellets to smoker according to manufacturer’s instructions.
Preheat smoker to 225°F.
Add beef to smoker. Set timer for 45 minutes.
Meanwhile heat oil in large skillet over medium heat until hot. Add onion, poblano peppers and garlic; cook 8 minutes, stirring occasionally, until softened. Add ancho chili powder, and salt and pepper as desired stirring occasionally until heated through, about 5 to 6 minutes. Take off heat, add in lime juice and stir until combined.
When beef is done smoking, carefully remove beef from smoker and finish on medium grill or in 350°F oven until roast reaches 145°F doneness, approximately 8 to 10 minutes. Tent with foil to keep warm.
Add chile and onion mixture to warmed tortillas. Top with beef slices. Garnish with toppings, as desired.
Nutrition information per serving: 438 Calories; 145.8 kcal Calories from fat; 16.2 g Total Fat; 0.8 g Saturated Fat; 0.2 g Trans Fat; 1.4 g Polyunsaturated Fat; 3 g Monounsaturated Fat; 79 mg Cholesterol; 63 mg Sodium; 44 g Total Carbohydrate; 5.8 g Dietary Fiber; 30.4 g Protein; 0 mg Calcium; 3.2 mg Iron; 611 mg Potassium; 0.3 mg Riboflavin; 8.1 mg Niacin; 0.9 mg Vitamin B6; 1.5 mcg Vitamin B12; 464 mg Phosphorus; 5.4 mg Zinc; 27.4 mcg Selenium; 99.6 mg Choline;