Steak Salad with Horseradish Dressing

Name: Steak Salad with Horseradish Dressing
Ingredients: ½ cup sour cream; 3 tablespoon prepared horseradish; 1 tablespoon chopped fresh chives; 1 teaspoon honey; 1 teaspoon red wine vinegar; Kosher salt and freshly ground black pepper; 2 tablespoon olive oil, divided; 1 1-lb. rib-eye, flank, or skirt steak; 12 ounces fingerling potatoes, thinly sliced; ½ English hothouse cucumber, thinly sliced; 6 radishes, cut into thin wedges; 2 cups greens (such as arugula or torn Bibb lettuce leaves); Pickled Red Onions