Creamy Veggie Salad

4 cups fresh broccoli florets
4 cups fresh cauliflowerets
1 package (10 ounces) frozen peas, thawed
5 green onions, sliced
1/2 cup reduced-fat sour cream
1/2 cup reduced-fat mayonnaise
1 to 2 tablespoons prepared horseradish
1/4 teaspoon salt
1/8 teaspoon pepper

In a large bowl, combine the broccoli, cauliflower, peas and onions. In a small bowl, combine the remaining ingredients; mix well. Pour over vegetables and toss to coat. Cover and refrigerate for several hours or overnight.