Instant Pot Corned Beef and Cabbage

Name: Instant Pot Corned Beef and Cabbage
Ingredients: 1 3 1⁄2-lb. pkg. uncooked corned beef brisket with spice packet; 1 cup unsalted beef broth; 1 ½ pounds yellow baby potatoes; 4 carrots, sliced into 2-in. pieces (about 2 1⁄2 cups); 1 head green cabbage, cut into 8 wedges, core intact; ⅔ cup sour cream; 2 tablespoons prepared horseradish; 1 teaspoon lemon zest plus 1 Tbsp. fresh juice (from 1 lemon); 2 tablespoons chopped fresh flat-leaf parsley, divided; 1 teaspoon freshly ground black pepper, divided