Scrub potatoes; prick with a fork. Tear off six 18x9-inch pieces of heavy foil. Fold each in half to make a 9-inch square. Wrap each potato in a foil square. Grill on an uncovered grill directly over medium-slow coals for 1 to 2 hours or until tender. Unwrap potatoes. Cool enough to handle. Cut potatoes in half lengthwise. Scoop out potato pulp, leaving 1/4-inch-thick shell. (Save potato pulp for another use.) Brush the inside of each potato shell with melted margarine. Spoon 2 tsp. Picante sauce into each potato shell. Sprinkle each with cheese. Add bacon. Grill potato skins on an uncovered grill directly over medium coals for 10 to 12 minutes or until skins are crisp. Sprinkle with tomato and green onion, if desired. Top with sour cream.
Makes 12 appetizer servings.