Place the chicken into the slow cooker and season with taco seasoning and cumin. Pour the salsa and black beans over the chicken.
Cover and cook on low for 4 hours or until the chicken is tender and easily shreds with 2 forks. Shred the chicken and stir to combine with black beans and the liquid in the slow cooker. Keep warm until ready to serve.
Combine all of the ingredients for the dressing in a blender and blend until smooth. If the dressing is too thick, add a little more buttermilk.
To make the salad—place 1 ½ cups of lettuce onto each plate, top with a ¾ cup of the chicken mixture, about 1 tablespoon of cheese and 2 tablespoons of the dressing.