Zest 2 of the limes. Squeeze the zested limes to yield 2 tablespoons of juice. In a small bowl, combine the zest, juice, sour cream, and ¼ teaspoon of the salt. Cut the remaining 2 limes into 6 wedges each. Set the sour cream mixture and lime wedges aside. In a large bowl, combine the vinegar, pepper, and ½ teaspoon of the remaining salt, whisking to dissolve the salt. Whisk in the oil. Add the cabbage and cilantro, tossing to combine. Set aside.