"This one's for my sister, Maria, who loves French cuisine but will not eat fish: a tuna Niçoise minus the tuna!" —Rach
Let the steaks come to room temperature, about 1 hour. Pat dry with paper towels.
Prepare an ice bath. In a medium pot, cover the eggs with a few inches of cold water. Bring to a boil over medium-high. Bring another medium pot of water to a boil for the haricots verts and potatoes.
Once eggs are boiling, cook for 8 minutes. Using a slotted spoon, transfer the eggs to the ice bath. Drain the eggs and peel under cold water. Halve the eggs lengthwise and set aside.
Meanwhile, heat a medium cast-iron skillet over medium-high. Coat with cooking spray. Season the steaks with the kosher salt and pepper. Add the steaks to the skillet and cook, turning once, about 3 minutes per side and 1 minute on each edge for medium-rare or 4 minutes per side and 1 1/2 minutes on each edge for medium to medium-well. Transfer the steaks to a cutting board to rest while you prep the eggs, haricots verts, and potatoes.
Salt the boiling water and add the haricots verts. Cook until crisp-tender, about 3 minutes. Using a slotted spoon, transfer to the ice bath. Let the haricots verts cool for a few minutes, then drain. Meanwhile, bring the water back to a boil over medium-high to high. Add the potatoes and boil until just tender when pierced with a small sharp knife, 10 to 12 minutes. Drain the potatoes and let rest until cool enough to handle, about 5 minutes. Quarter the potatoes.
For the dressing, in a large bowl, whisk the anchovies, if using, garlic, shallot, and lemon juice. Let stand for a few minutes. (If not using the anchovies, mix the garlic and shallot with some salt and let sit for a few minutes until they release their juices, then whisk in the lemon juice.) Whisk in the vinegar, Dijon, and herbes de Provence. Slowly stream the EVOO along the side of the bowl, whisking constantly until the dressing is smooth. Season with salt, if needed.
Thinly slice steaks across the grain.
Remove 1/4 cup of the dressing from the bowl. Add greens to remaining dressing and toss to coat. Divide the salad among large plates. Top with the haricots verts, potatoes, olives, tomatoes, eggs, and sliced steak. Drizzle with the remaining dressing.