Core strawberries by cutting around the stem; do not cut through the bottom of the strawberry. Slice a small piece of the tip of the strawberry off so it will stand without tipping over.
Whip cream in a chilled bowl with the whisk attachment of a stand or hand mixer until soft peaks form. Whisk in sugar. Remove to medium-size bowl and set aside.
Whisk together the Mascarpone or cream cheese and lemon curd. Fold whipped cream into cheese mixture until uniformly mixed. Chill until ready to use.
Pipe or spoon lemon cream mixture into each strawberry. Top with a blueberry and garnish with a mint leaf. Chill or serve immediately (can be made several hours ahead).