Combine the marinade ingredients together in a shallow baking dish; add the chicken breast making sure they are completely covered with the marinade. Cover and refrigerate for at least an hour or preferably overnight. When ready to assemble either BBQ or grill and allow to cool. When cooked breast meat has cooled, shred by pulling apart with fingers.
Process all of the above ingredients in a blender until smooth, season to taste.
Combine all ingredients and season with salt and pepper to taste.
To assemble tortillas: Warm tortillas in the oven or lightly pan fry brushed with oil in a hot pan for about 30 seconds each side. Place one tortilla per serving plate, loading with a lettuce leaf on top, shredded chicken, salsa and garnish ingredients as desired. Serve with green sauce.