In a small bowl, whisk together the smoked paprika, garlic powder, onion powder, sea salt, and black pepper to create the BBQ rub.
Rub the spice mixture evenly over both sides of the flank steak and let it sit for 10 minutes at room temperature to absorb the flavors.
Bring a small pot of water to a boil and blanch the trimmed green beans for 3 minutes until tender-crisp, then immediately plunge them into ice water to stop the cooking.
In a medium bowl, whisk the extra virgin olive oil, lemon juice, and Dijon mustard until the dressing is fully emulsified.
Toss the blanched green beans, drained chickpeas, and chopped fresh parsley into the dressing until every ingredient is well coated.
Preheat a grill or cast-iron skillet over medium-high heat and sear the steak for 4-5 minutes per side for a perfect medium-rare finish.
Transfer the steak to a cutting board and let it rest for 5 minutes to allow the juices to redistribute before slicing thinly against the grain.
Arrange the sliced steak on a plate alongside the chilled green bean and chickpea salad and serve immediately.