If you use non-dairy milk this is a vegan treat because it sets with kanten, the seaweed gelatine.
Combine and let sit in saucepan for 10 minutes:
2 C pureed strawberries
1 C milk (rice milk, strained almond milk, or cream or milk)
3/4 tea kanten/agar-agar powder
1-2 TB sugar (to taste)
Bring the mixture to a gentle simmer for a few minutes, stirring until kanten is incorporated.
Pour into lightly greased individual ramekins. Chill until set (40 min to an hour).
When ready to serve, carefully remove panna cotta from ramekins and invert onto serving plates.