Sprinkle the gelatin evenly over the cold water in a small bowl and set aside for a few minutes to fully hydrate. Combine the heavy cream, sugar and salt in a small saucepan and bring to a simmer over a medium-low heat. When the cream just about simmers, whisk in the gelatin. Take off the heat and leave to cool for about 10 minutes before stirring in the kefir and vanilla extract. Adding the kefir when the cream is too hot may cause the mixture to split. Portion the panna cotta into cups or glasses, and chill in the refrigerator overnight.

To serve, halve or quarter the strawberries depending on their size. Toss in a small bowl with the sugar, lime zest and juice. You may need to use more or less sugar depending on how sweet the berries are to begin with. Let the berries macerate for about 15 minutes, then spoon over the cold panna cotta and serve right away.

*Gelatin’s setting power becomes stronger the longer it sits. The amount of gelatin specified in this recipe is perfect for creating a softly jiggling panna cotta when it has rested for about 18 hours. If you are making the panna cotta more than 1 day ahead, reduce the gelatin to 1 teaspoon so you don’t end up with an overly firm or rubbery panna cotta.

Seasonal variation: This panna cotta is also lovely served with roasted rhubarb. For this, you need 200 grams of rhubarb, chopped into 1 inch lengths. Toss with 50 grams of sugar and place in a small ovenproof dish. Pour in a quarter cup of orange juice, red wine or water and cover tightly with aluminum foil. Roast in a 400° oven for about 15 minutes or until the rhubarb is tender but not mushy.