Cook brown rice following package directions.
Heat oven to 400 degree F. Coat 2 baking sheets with nonstick cooking spray. Place 6 tortillas on each and coat with cooking spray. Bake at 400 degree F for 8 to 10 minutes.
Place lime juice and shrimp in a resealable plastic bag and toss. Let marinate at room temperature for 5 minutes. Heat oil in a large nonstick skillet on medium high. Add shrimp mixture, garlic and half the scallions; saute for 2 minutes, stirring. Season with salt. Stir in barbecue sauce and rice.
To serve, top each tortilla with about 1/3 cup of lettuce and 1/4 cup of the shrimp mixture. Sprinkle each with remaining scallions and pickled jalapenos, if using.
Makes 6 servings.