Take the flank steak and put it in a resealable plastic food storage bag.
In a small bowl combine and mix together well the soy sauce, jalapeños, brown sugar, and garlic and pour the mixture over the flank steak.
Seal the bag so that it is securely closed and turn the bag to coat steak, then marinate in refrigerator for 2 hours.
Preheat the broiler.
Drain the steak in the bag and throw out the marinade. Take the steak and place it on rack of broiler pan and broil steak for 18 to 23 minutes for medium rare to medium or until desired doneness, broiling 4 inches from heat and turning once.
Remove the steak from the heat and let it stand for 15 minutes.
Slice the steak thinly across grain then in a large bowl toss with lime juice, green onions, carrots and cilantro and serve salad immediately over lettuce leaves.