Season the steak with salt and freshly ground black pepper, herbs de Provence, and minced garlic. In a skillet, heat 3 tablespoons olive oil over medium heat. Cook steak about 7 minutes per side. Remove the meat from pan and let it rest for 5 minutes. Thinly slice the steak. Set aside.
Meanwhile, bring a large pot of salted water to a boil over high heat. Add the pasta and cook until tender but still firm to the bite, stirring occasionally, about 8 to 10 minutes. Drain pasta, reserving 1/4 cup of pasta water.
In a small bowl, whisk together the balsamic vinegar, Dijon mustard, 1/2 teaspoon salt, 1/2 teaspoon pepper, fresh herbs, and 3/4 cup olive oil. In a large bowl toss the pasta with half of the salad dressing and the reserved pasta water. Add the arugula and steak, more dressing, and season with salt and freshly ground black pepper, as needed. Toss, pack for the picnic, or serve.