Pour chipotle peppers and adobo sauce into a blender. Add 2 cups buttermilk; cover and process until peppers are completely pureed.
Place chicken in a large zip top plastic bag and pour buttermilk mixture and remaining buttermilk over chicken. Refrigerate for at least 3 hours or up to overnight.
Combine the masa, panko, salt and pepper in a large zip top plastic bag. Drain chicken pieces; add to masa mixture, 1 at a time, and shake to coat. Shake off excess; place on waxed paper for 15 minutes before frying.
Heat 4 inches of oil to 375 degrees F in a large cast iron skillet.
Fry chicken for about 4 minutes on each side or until browned on all sides. Remove chicken from skillet and place on a paper towel lined platter. Once well drained, keep chicken warm on a wire rack over a baking sheet in a oven preheated to 300 degrees F.
Serve chicken on a large platter with Cool Cucumber Slaw. Garnish with Cilantro and cucumber wedges.
Cool Cucumber Slaw:
Stir together the cucumber and salt. Place in a colander over a mixing bowl. Refrigerate for 1 hour. Discard liquid and place cucumber in mixing bowl. Add yogurt, lime juice, mint, cilantro, carrot, scallion and sugar to the cucumber. Mix until well combined. Cover and refrigerate at least 3 hours, preferably overnight.