Wash and peel 7 stalks of rhubarb.

Trim the ends and cut the rhubarb into chunks.

Combine the rhubarb pieces, water, sugar, orange zest, and cinnamon sticks in a saucepot.

Bring to a simmer over medium heat.

Cook until the rhubarb is falling apart, approximately 8 to 12 minutes.

Test for doneness by piercing with a sharp knife; remove from heat once easily penetrated.

Transfer the contents to a shatter-proof container.

Refrigerate the soup until cold (about 2 hours).

Discard the cinnamon sticks.

Juice the remaining rhubarb stalk (optional, or use lemon juice).

Strain the rhubarb juice (or lemon juice) and add it to the chilled soup.

Serve the soup in chilled dessert bowls.

Top with a scoop of vanilla ice cream, sliced strawberries, blueberries, and torn mint leaves.