1. Rub the steaks with the oil and season with salt and pepper.
2. Place steak on grid over medium heat. Grill, uncovered, 17 to 21 minutes for medium rare to medium or until desired doneness, turning once. After both sides cooked, let rest for 10 minutes before slicing thinly.
3. To make dressing, in a small skillet, heat the water with the sugar, stirring until dissolved. Transfer to a large bowl. Add the garlic, fish sauce, lime juice and chile-garlic sauce and let cool. Add the cucumber, onion, tomatoes, chinese celery, mint and sliced steak and toss well. Sprinkle with the peanuts and serve right away.