Whisk together lime juice, brown sugar, ginger, fish sauce, and chile paste.
Heat a cooking spray coated frying pan over medium-high heat. Season both sides of steak with pepper. Cook steak 6 minutes per side or until preferred degree of doneness. Take steak out of pan and let rest on a cutting board, tented with foil for 5 minutes. Slice steak diagonally across grain into thin pieces. Put steak in a bowl and toss with half the dressing.
Combine watercress, cabbage, basil, mint, cilantro, and carrots. Toss with the rest of the dressing and top with steak and peanuts.