How to make fresh watermelon jello without gelatin, using watermelon juice and agar-agar for a healthy, delicious, all-natural, vegan jello! Serve in the rind for show-stopping watermelon jello slices, pour into watermelon jello shots, or simply set in a large jello mold for a fruity, summery treat.
Slice the watermelon in half and juice it. To do so, just scoop out the watermelon flesh from the rind, place it in a large bowl and use an immersion blender; or use a large blender/food processor. Blend until smooth.If you plan to use the watermelon rind for the jello, use a spoon to gently scrape all the flesh from the melon until the light rind.
Strain the juice to remove any seeds/pulpy bits. I use a nut milk bag and manually squeeze. A fine-mesh sieve would also work.
Step 2: Prepare the jello mixture
In a large skillet or saucepan, combine the watermelon juice and agar-agar and heat over medium, whisking constantly, until the agar has completely dissolved. This process will take just a few minutes.
Once melted, work quickly to pour the mixture into the watermelon rind OR the mold of your choice. If you're making watermelon shots, then add to individual shot glasses.
Allow the mixture to cool down and chill in the refrigerator until fully set. The amount of time this takes will depend on what mold you've used (i.e., watermelon jello shots will take far less time than using the watermelon rind).
Then use a chilled sharp knife (place it in the freezer for a few minutes) to slice the watermelon jello slices and serve! Serve alone, studded with mini chocolate chips (as "seeds"), or top with a bit of whipped coconut cream and berries!
How to Store?
Once prepared, the watermelon jello will store for several days (3-4) in the fridge. In fact, you don't even have to fully slice the melon slices until you're ready to serve if preferred.¾
For smaller slices: instead of watermelon rind, you can pour the watermelon jello into scooped out lime halves, then slice into wedges once set. Though the jello will become tarter nearer to the rind.
Trim the slices: even if you pour the watermelon jello to the top of the watermelon rind, it will shrink as it sets. For "pretty" slices, I recommend trimming off the ends of the rind after cutting the slices.
Leaving some flesh in the slices: it's possible to leave a thin 1-inch layer of watermelon flesh in the melon before adding the jello. If you have any extra, you can just pour it in a separate mold. However, I've found that the jello is more likely to slide off the rind when flesh remains.
Making the perfect slice: it's important to slice fairly substantial pieces (around 1-inch thick minimum). Slice them too thin, and the jello will flop over rather than stand.
What is agar-agar powder? It is a substance made from seaweed (specifically red algae) that becomes gelatinous when heated, similarly to gelatin – yet is 100% plant-based. In comparison, it sets slightly firmer than gelatin and doesn't require being chilled to fully set.
Can I substitute the agar? Technically you could use veggie gel (the vegetarian version of gelatin) or gelatin (if you use animal products). However, the amounts will differ (written on the packs), and I can't guarantee results, as I haven't tried.
Optional Add-Ins and recipe variations:
Sugar: if the watermelon is sweet enough, you may not need any at all (I didn't). However, you can add sugar (or a sugar-alternative like erythritol/Stevia) to the juice when heating. Use cane sugar, coconut, etc. However, each will affect the flavor in different ways.
Lemon/Lime: a little lime zest and juice added to the jello mixture will enhance flavor and add a little zing.
Rosewater: just a little rosewater will help to subtly fragrance the watermelon jello recipe. I recommend adding 1 teaspoon and only then increasing to taste. Alternatively, you could add a few drops of rose extract.
Alcohol: for boozy watermelon jello shots, you could use vodka, tequila, or rum. Just note that you'll need to add extra agar-agar to make up for the excess liquid. Use around ½ teaspoon agar powder for ½-3/4 cup alcohol (otherwise, the watermelon jello slices won't be stiff enough). If you want vegan watermelon jello, make sure your alcohol is vegan!