Method:

• Heat oven to 350°F (180°C). Line 15x10x3/4-inch (38x25x2 cm) jelly roll pan with parchment paper.
• Beat cake mix and cold water in extra-large glass or metal bowl on low speed 30 seconds; beat on medium speed 1 minute. Spread half of the batter in jelly roll pan. Pour remaining batter in ungreased 9x5-inch (23x13 cm) loaf pan.
• Bake jelly roll pan 20 to 25 minutes, loaf pan 35 to 45 minutes, or until top springs back when touched lightly in centre. Reserve loaf pan for another use. Cool jelly roll pan 10 minutes. Loosen cake from edges of pan; turn upside down onto towel sprinkled with icing sugar. Carefully remove parchment paper. Trim off stiff edges of cake if necessary. Carefully roll hot cake and towel from narrow end. Cool completely on wire rack, about 1 hour.
• Unroll cake; remove towel. Beginning at a narrow end, spread raspberry sherbet on one-third of cake, orange sherbet on next third of cake and lime sherbet on remaining cake. Roll up carefully. Place roll, seam side down, on 18x12-inch (45x30 cm) piece of foil. Wrap in foil; freeze at least 6 hours until firm. Remove from freezer 15 minutes before serving. Cut roll into 3/4-inch (2 cm) slices. Store wrapped in freezer.