1. Combine chopped rhubarb and water in a medium saucepan. Simmer over medium heat until the rhubarb softens and breaks down completely, about 10-12 minutes. Stir occasionally to prevent sticking.

2. Remove from heat and let cool slightly. Transfer to a blender or use an immersion blender to purée until completely smooth. Strain through a fine mesh sieve for extra smoothness if desired.

3. Return the purée to the saucepan. Stir in sugar, lemon juice, and optional honey. Simmer over low heat until the mixture thickens, about 10 more minutes, stirring often to prevent burning.

4. For faster thickening, mix cornstarch with 2 tablespoons water to make a slurry. Stir into the simmering rhubarb mixture and cook, stirring constantly, until noticeably thickened.

5. Line a baking sheet with parchment paper or a silicone mat. Pour the thickened mixture onto the sheet and spread evenly to about 1/8 inch thickness. Work quickly before it starts to set.

6. Dehydrate in the oven at the lowest temperature setting, around 150-170°F. This takes 6-8 hours. The belts are ready when dry and tacky but still pliable, not brittle.

7. Remove from the oven and let cool completely. Use kitchen scissors or a pizza cutter to slice into long belts. Toss in a mixture of superfine sugar and citric acid for the sour coating.