Preheat a grill or cast-iron skillet to medium-high heat.
Rub the flank steak with one teaspoon of olive oil, sea salt, and black pepper.
Slice the red bell pepper and zucchini into thick, grill-friendly strips.
Grill the steak for 4 to 5 minutes per side for medium-rare, then transfer to a cutting board to rest for 10 minutes.
While the steak rests, grill the vegetable strips until tender and slightly charred.
In a small bowl, whisk together the extra virgin olive oil, balsamic vinegar, dijon mustard, and garlic powder.
Place the arugula in a large bowl and toss with half of the prepared dressing.
Slice the rested steak against the grain into thin strips.
Top the dressed arugula with the grilled vegetables and steak, then drizzle with the remaining dressing.