1. Pierce potatoes with fork. Microwave on HIGH 30 minutes, turning after 15 minutes; let cool. Cut potatoes in half; scoop out centers, leaving 1/4-inch shell. Reserve potato pulp for another use.
2. Brown beef in large skillet over medium-high heat 6 to 8 minutes, stirring to break up meat. Drain fat. Stir in water and taco seasoning; bring to a boil. Reduce heat to low; cook, uncovered, 15 minutes. Stir in green onions.
3. Preheat broiler. Spoon meat mixture into potato shells; top with tomato, olives and cheese. Place filled potato shells on baking sheet; broil until cheese is melted. Top with Quick Taco Dip, if desired.
Quick Taco Dip
Combine 2 cups sour cream and 1 package (1-1/4 ounces) taco seasoning mix in medium bowl; mix well. Refrigerate until ready to serve. Makes 2 cups.