In a medium bowl, whisk together 2 tablespoons olive oil, lemon juice, paprika, 1 teaspoon salt, and ½ teaspoon black pepper. Add the flank steak, turning to coat completely, and marinate for 15-30 minutes at room temperature.
While the steak marinates, prepare quinoa or couscous according to package directions. Quinoa typically takes 15-20 minutes; couscous takes about 5-10 minutes. Set aside and keep warm.
Preheat grill or stovetop grill pan over medium-high heat (about 400-450°F). Grill the marinated flank steak for 6-8 minutes per side for medium-rare (internal temperature 130-135°F), or until desired doneness is reached.
Remove steak from heat and let rest on a cutting board for 5 minutes. Slice thinly against the grain at a slight angle.
In a large bowl, combine cherry tomatoes, cucumber, bell pepper, red onion, and chickpeas. Drizzle with remaining 1 tablespoon olive oil, season with salt and pepper, and toss gently.
Divide the quinoa or couscous among 4 serving bowls. Top each with sliced steak, vegetable mixture, crumbled feta cheese, and Kalamata olives. Sprinkle fresh parsley over top and serve immediately.
