In Dutch oven, place steamer basket over 1/2 inch deep water (water should not touch basket.) Cut cabbage (about 1 1/2 pounds) into 6 wedges and quarter potatoes. Place cabbage and potatoes in basket, cover tightly and heat water to boiling. Reduce heat to medium-low and steam 20-30 minutes or until tender. Meanwhile, in a 1 cup glass measure, combine butter, sliced green onions, horseradish, salt and pepper. Microwave on high 45 seconds or until butter is melted. Drizzle over vegetables.