In a large bowl, combine the sliced flank steak, olive oil, onion, bell pepper, garlic powder, chili powder, cumin, smoked paprika, salt, and black pepper. Toss until the steak and vegetables are evenly coated with the spices.
Place the mixture into the slow cooker and pour the beef broth over it. Stir to combine.
Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the steak is tender and the flavors are well blended.
Once cooked, shred the steak using two forks and mix it back with the vegetables and juices in the slow cooker.
Warm the flour tortillas in a skillet or microwave.
Serve the steak fajitas in tortillas, garnished with fresh cilantro and lime wedges on the side.