Choosing beef from healthfully raised cows is important nutritionally, ecologically and politically. If you can't find grass-fed or humanely raised beef from a local farmer, ask questions at your food co-op or grocery store to find beef from cows that were not given antibiotics or hormones. Grass-fed beef requires a shorter cooking time because the beef is less fatty.
Combine lime juice, oil, cilantro, garlic, hot pepper, honey, salt and pepper to taste in a small bowl to make marinade. Whisk together and set aside.
Place sirloin between two sheets of plastic wrap and pound on both sides to tenderize. Remove wrap and place sirloin in a shallow pan. Pour half of the marinade over the meat. Cover and marinate in the refrigerator for at least 1 hour or up to 12 hours.
Preheat oven to 390 degree Fahrenheit. Heat a cast iron or oven-safe skillet with a teaspoon or so of oil. Place marinated steak in skillet and brown for a few minutes on each side. This is a good time to salt and pepper the meat. Transfer steak to the oven for 7 to 10 minutes. Check center for doneness (red for medium rare, pink for medium) and remove from oven when it is redder than you desire; the meat will continue to cook once it is out of the oven.
While meat is cooking, prepare noodles according to package directions.
Transfer meat to a carving board and let rest 10 minutes before slicing into thin slices on a diagonal against the grain of the meat. To assemble, place a small bed of noodles on each plate. Toss the greens, onion and cucumber with almost all of the remaining marinade and divide among four plates. Top each plate of noodles and salad with an equal portion of steak slices and a drizzle of dressing.