PLACE broth, 1/4 cup of the dressing, the ancho peppers and oregano in blender; cover. Blend on medium speed 1 min. Pour into large resealable plastic bag. Add steak; seal bag. Turn bag over several times to evenly coat steak with the broth mixture. Refrigerate overnight to marinate, turning occasionally.
MIX potatoes, carrots, serrano chiles, bacon and 2 Tbsp. of the cilantro; set aside. Remove steak from marinade; reserve marinade in bag. Place steak on clean work surface. Spread evenly with potato mixture to within 1/2 inch of edges. Roll up tightly, starting at one of the short ends. Tie securely with kitchen string at 2-inch intervals; set aside.
HEAT remaining 1/4 cup dressing in large skillet on medium-high heat. Add steak; cook until browned on all sides, turning occasionally. Add reserved marinade; bring to boil. Reduce heat to low; cover. Simmer 1 hour 45 min. or until steak is medium doneness (160°F). Transfer steak to cutting board; let stand 10 min. Remove string; cut steak into 1/2-inch-thick slices. Place on serving platter. Spoon broth mixture over steak slices; sprinkle with the remaining 2 Tbsp. cilantro.