Mix soy sauce, 6 tablespoons of the lime juice, brown sugar, fish sauce, chilies, garlic powder and ginger in small bowl. Reserve 3 tablespoons of the marinade for brushing steak during grilling.
Remove another 3 tablespoons of the marinade into another small bowl. Add peanut butter, water and remaining 1 tablespoon lime juice; mix well. Set peanut sauce aside until ready to serve.
Place steak in large resealable plastic bag or glass dish. Add remaining marinade; turn to coat well. Refrigerate 30 minutes or longer for extra flavor. Remove steak from marinade. Discard any remaining marinade.
Grill steak over medium-high heat 6 to 8 minutes per side or until desired doneness, brushing with reserved marinade halfway through cooking. Slice steak and serve with Savory Peanut Sauce.