Bring 3/4 cup water to boil in a small saucepan over medium-high heat. Whisk the gelatin into the hot water until fully dissolved, then turn off the heat. Add the large piece of orange zest and let steep for 5 minutes.
Remove the orange zest from the strawberry gelatin mixture. Whisk in the rum, orange liqueur, lime juice and orange juice, then skim off any foam with a spoon. Transfer to a resealable plastic bag and chill in the fridge until the mixture has a slight jiggle, about 30 minutes.
Meanwhile, trim off the tip of each strawberry to create a steady base so that it can stand up. Gently hull each berry, being careful not to pierce through the sides or bottom, then enlarge this hole slightly. Place the berries into a muffin tin. (If you have a mini muffin tin, sit one berry in each cup; if using a standard tin, try to nestle 2 into each cup.)
Trim a small corner from the plastic bag and pipe the mixture into each berry, being careful not to overfill. Refrigerate until the gelatin has fully set and does not stick to your finger if you touch it, about 4 hours.
Top each berry with whipped cream and sprinkle with green sanding sugar. Enjoy!