In an extra-large bowl combine beans, piquante peppers, onion, and vinegar. Add lettuce and arugula; toss to combine. Sprinkle with salt and black pepper.
Sprinkle both sides of meat with salt and black pepper. In a 12-inch heavy skillet heat oil over medium-high heat. Add meat; cook 4 to 8 minutes for medium-rare (145°F), turning once. Remove from skillet. Cover with foil; let stand 5 to 10 minutes. Thinly slice meat across the grain.
Meanwhile, for dressing, in a small bowl whisk together yogurt, ranch dressing mix, and enough of the water to reach drizzling consistency. Drizzle dressing over lettuce mixture and sliced meat.