1Place tomato halves in 1 inch water in 1 1/2-quart saucepan. Heat to boiling; reduce heat to medium. Simmer uncovered about 5 minutes or until water has evaporated.
2Place tomatoes and remaining ingredients except yogurt and sour cream in blender or food processor. Cover and blend on medium-high speed until smooth.
3Place tomato mixture in medium glass or plastic bowl. Stir in yogurt and sour cream. Cover and refrigerate about 2 hours or until chilled.