On a baking sheet, broil the jalapeno peppers, turning occasionally, for 7-10 min. or until blackened. Let cool slightly. Remove skins and seeds, chop finely.
Stir 1 tsp. of the chopped jalapeno into the mayo and set aside.
In a bowl, mix the couscous with salt. Add 2/3 cup boiling water, stir once then cover and set aside for 10 min.
Whisk together the remaining jalapeno, oil, lime juice, 1 Tbsp. water, sugar, and pepper. Stir into couscous. Stir in avocado, corn, and tomato.
Meanwhile, stir together oil, chili powder, and oregano, and then brush all over the chicken. Broil on a greased baking sheet for about 5 min. per side or until chicken is no longer pink inside. You can BBQ the chicken if you prefer. Cut chicken into thin strips.
Take tortilla shells of your choice and spread the mayo mixture over each tortilla, leaving a 1" border.
Starting just below the center of the tortilla, mound couscous filling, top with chicken, and fold and roll up as usual for a tortilla.