Peel and cut sweet potatoes into 1/2" cubes. Boil the sweet potatoes in a pot of salted water until tender, 5-7 minutes. Drain then rinse under cold water until cool. Combine with pineapple and parsley.
Whisk mayonnaise, yogurt, sugar, 2 teaspoons lime juice, and vanilla together in a dish. Season with salt and white pepper; toss with the potato mixture to coat.
Combine blackening spices in a small bowl, then rub the mixture on both sides of the ham steak (16-20 ounces). Grill (or use stove-top grill pan) until the edges of the steak begin to curl; flip the steak and grill 1-2 more minutes. Serve with sweet potato salad.