Combine the first 4 ingredients in a heavy-duty zip-top plastic bag. Add chicken; seal and shake to coat. Remove chicken from bag. Combine the buttermilk and next 5 ingredients (buttermilk through garlic) in a small bowl, and stir well with a whisk.
Place a large nonstick skillet over medium-high heat until hot. Add chicken, and sauté 2 minutes or until chicken is done. Add the buttermilk mixture; cover and cook 1 minute. Remove from heat.
Warm the tortillas according to the package directions. Spoon about 3/4 cup chicken mixture onto each tortilla, and top each serving with 3/4 cup chopped lettuce and 1/3 cup chopped tomatoes. Roll up wrap.