Spiced Shish Kebabs with Horseradish Cream

1 pound boneless top sirloin steak, all visible fat discarded, cut into 1-inch cubes2 teaspoons chili powder2 teaspoons dried oregano, crumbled1 teaspoon ground cumin 3/4 teaspoon garlic saltVegetable oil sprayHorseradish cream 1/3 cup fat-free sour cream2 tablespoons fat-free or light mayonnaise dressing1 tablespoon prepared white horseradish 1/2 teaspoon garlic salt1 large red onion (about 6 ounces), quartered and layers separated1 medium yellow bell pepper, cut into 1-inch pieces16 cherry tomatoesChili powder to tastePut the steak in a shallow bowl. Sprinkle with the chili powder, oregano, cumin, and 3/4 teaspoon garlic salt. Toss gently yet thoroughly to coat completely. Let stand for 15 minutes to absorb flavors.Meanwhile, heat the broiler. Lightly spray the broiler pan and rack with vegetable oil spray.For the horseradish cream: In a small bowl, stir together the sour cream, mayonnaise, horseradish, garlic salt. Sprinkle the chili powder on top.Thread the vegetables and meat onto four 12-inch metal skewers in alternating order: onion, bell pepper, tomato, and steak. Put the kebabs on the prepared rack. Broil the kebabs about 4 inches from the heat for 4 minutes. Turn the kebabs and broil for 3 minutes, or until desired doneness. Serve with the horseradish cream.Serves four.Nutrition values per serving: 223 calories, 6 g fat (2 g saturated), 17 g carbohydrates, 3 g fiber, 25 g protein, 67 mg cholesterol, 461 mg sodium."American Heart Association Low-Fat, Low-Cholesterol Cookbook" (2004 Clarkson Potter)