Step 1

To prepare puree: Puree 1 1/2 cups raspberries, 1 cup strawberries, orange juice and lemon juice in a blender until smooth. Add sugar to taste. Set aside at room temperature for up to 3 hours or cover and refrigerate.

Step 2

To prepare sauce: Place lemon curd in a medium bowl and gradually stir in sour cream (or creme fraiche or yogurt). Transfer to a serving dish, cover and refrigerate until ready to serve.

Step 3

To prepare berries: If refrigerated, remove berries and the berry puree from the refrigerator about 3 hours before serving to bring them to room temperature. (Room-temperature berries and puree have the best flavor.) About 1 hour before serving, hull and quarter the strawberries and combine with the blueberries and blackberries in a large mixing bowl. Toss with the puree. Adjust the sweetness if necessary by gradually adding sugar to taste, 1 tablespoon at a time. Cover and let stand at room temperature.

Step 4

Just before serving, add the raspberries to the bowl, tossing very gently with two spoons and being careful not to break up the berries. Transfer to a serving dish, if desired, and garnish with mint. Serve each portion of berries topped with about 2 1/2 tablespoons of the lemon sauce.