In a small bowl, mix together the smoked paprika, garlic powder, onion powder, dried oregano, cumin, salt, and pepper to make the dry rub.
Brush the flank steak with olive oil on both sides, then generously apply the dry rub, pressing it into the meat. Place the steak in a large dish, cover with plastic wrap, and refrigerate for at least 2 hours or overnight
Preheat the smoker to 225°Fahrenheit.
Remove the steak from the refrigerator and let it sit at room temperature for 20-30 minutes.
Place the steak in the smoker and smoke for 30-40 minutes, or until the internal temperature reaches 130-135°F for medium-rare.
Remove the steak from the smoker and let it rest on a cutting board for 10 minutes.
Slice the steak thinly against the grain.
Notes
Letting the steak marinate for at least 2 hours, or even better, overnight, really helps the flavors soak in and tenderizes the meat, which is very important for a tougher cut like flank steak.