With the rack in the middle position, preheat the oven to 350°F (180°C).
In a bowl, combine the graham cracker crumbs and butter. Lightly press onto the bottom and up the sides of a 9-inch (23 cm) pie plate. Bake for 12 minutes, then let cool on a wire rack.
In a bowl, sprinkle the gelatin over the water. Let bloom for 5 minutes. Set aside.
In a pot over medium heat, gently heat the sugar with 1/4 cup (60 ml) of the yogurt just until the sugar has dissolved, stirring constantly. Remove from the heat. Add the gelatin mixture and whisk until completely dissolved. Stir in the remaining yogurt and the kefir. Pour into the crust. Cover with plastic wrap directly on the surface of the cream. Let cool, then refrigerate for 4 hours or just until the filling has set.
When ready to serve, garnish with the fruit and mint.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.