Crisp the phyllo shells in the oven according to the package directions and set aside until ready to serve.
In a sauce pan add the chicken, chipotles, ketchup, brown sugar, soy sauce, vinegar and chili powder and simmer over medium-low heat for about 8-10 minutes or until heated through and sauce is syrupy.
In another bowl, mash the avocado, yogurt and lime juice together. Then add the chopped cilantro and salt to taste. (can use purchased guacamole if desired)
Fill each phyllo shell with a dollop of avocado mixture and top with chicken. Garnish with a cilantro leaf and lime zest if desired.