Preheat oven to 375 degrees F. Place potatoes in a 15x10x1-inch baking pan. Drizzle with 1 tablespoon of the olive oil; sprinkle with salt and pepper. Toss to combine. Roast, uncovered, 50 to 60 minutes or until tender. Cool slightly.
Meanwhile, brush remaining 1 tablespoon of olive oil on steaks. Season with salt and pepper. For charcoal grill, grill steaks on rack of uncovered grill directly over medium coals, 10 to 12 minutes (145 degrees F for medium-rare), turning once. (For gas grill, preheat grill. Reduce heat to medium. Place steaks on rack over heat. Cover; grill as above.)
Slice romaine into six 2-inch-thick slices, reserving tops for another use. Prepare Salsa Verde.
Place slice of romaine on each serving plate; drizzle; with 1/2 of the Salsa Verde. Toss warm potatoes with remaining sauce and green onions. Spoon onto romaine. Thinly slice steak and place on top of potatoes. Makes 6 servings.
In bowl combine parsley, extra-virgin olive oil, chives, capers, oregano, thyme, and garlic. Season with salt and pepper.