Preheat your grill or a cast-iron skillet over medium-high heat.
Rub both sides of the flank steak evenly with the smoked paprika, sea salt, and black pepper.
Place the steak on the hot grill and cook for 4 to 5 minutes per side for medium-rare, or until it reaches your preferred doneness.
Transfer the steak to a cutting board and let it rest for at least 5 minutes to lock in the juices.
While the steak rests, combine the baby arugula, halved cherry tomatoes, sliced cucumber, and thinly sliced red onion in a large salad bowl.
In a small jar or bowl, whisk together the lemon juice, lemon zest, and extra virgin olive oil to create the dressing.
Slice the rested steak thinly against the grain, then toss the salad with the dressing and top with the steak and sliced avocado.