1. In small saute pan add orange juice, sugar and agar powder over medium heat. Whisk to combine, and bring to just a boil, stirring constantly. Mixture will start to thicken
2. Remove from heat and whisk in rum
3. Pour mixture into molds, ramekins, ice cube trays, etc. Let set at room temperature 15-30 minutes or place in refrigerator to speed up the process
4. Once firm, gently run a round-edged knife around or under the gel and serve as dessert or gently roll and place in a cocktail glass and garnish with fresh fruit

Adapted from "Cooking for Geeks" by Jeff Potter