Prepare outdoor grill. Season steak with salt and pepper, place on grill, and cook for about 5 minutes, turn and cook for 3 to 4 minutes more, or until meat is cooked rare. Remove from heat and let rest.
In large bowl, toss together the greens, cilantro, and mint leaves.
Cut meat across the grain and arrange slices on top of greens.
Spoon 1/4 of the sauce over each portion, garnish with mint leave and a lime wedge and serve immediately.
For sauce combine garlic, chiles, fish sauce, lime juice and sugar in small bowl.