Grilled Cabbage Wedges with Buttermilk Ranch

Name: Grilled Cabbage Wedges with Buttermilk Ranch
Ingredients: Oil, for the grill pan; 1/2 small green cabbage, cut into wedges (see Cook's Note); 1/2 small red cabbage, cut into wedges (see Cook's Note); 2 teaspoons Cajun or Creole seasoning; 1/2 cup whole buttermilk; 1/4 cup mayonnaise; 1 tablespoon chopped fresh parsley, plus more for sprinkling; 1 teaspoon Miss Brown’s House Seasoning, recipe follows; 1/2 teaspoon lemon zest plus 1/2 teaspoon lemon juice; 1/4 teaspoon dried dill; 1/4 teaspoon dry mustard; Kosher salt and freshly ground black pepper; 1 teaspoon garlic powder; 1 teaspoon onion powder; 1 teaspoon sweet paprika; 1 teaspoon kosher salt; 1 teaspoon freshly ground black pepper