Roughly chop strawberries, and toss with sugar. Leave for an hour (or more) for juice to release.

Strain 1 cup of juice into a small sauce pan, reserving 3 tablespoons.

Bring strawberry juice to simmer, and cook on low for 10-15 minutes. This will reduce the juice and concentrate strawberry flavor. Cool.

Transfer strawberries and reduced juice to a high-powered blender, mix until completely smooth. Transfer to a Mason jar (I use 1/2 gallon jar, even though it's too big - it leaves room for shaking). If you don't have a high-powered blender, you would need to strain strawberry mixture to remove the seeds, it's kind of a hassle.

Combine reserved 3 tablespoons juice and 1.5 teaspoons of gelatin in your smallest sauce pan. Allow to sit for a few minutes, for gelatin to hydrate. Turn on the flame, and gently warm up until the gelatin just melts, don't bring it to boil.

Add gelatin mixture to the strawberry jar, shake. Add kefir and vanilla. Shake well until no white kefir grains remain.

Serve cold.