Gather all ingredients.

Place rhubarb in a large saucepan with water to cover. Bring to a boil over medium-high heat and cook until tender.

Drain; mash or purée in a blender.

Stir together rhubarb purée, sugar, orange juice concentrate, lemonade concentrate, gin, and water.

Freeze for 1 to 3 hours, depending on the consistency you like.

Place scoops of the frozen mixture into serving glasses and fill the rest of the glass with lemon-lime soda.