This vibrant and fresh dessert can be made up to one week ahead of time. To do so, simply overwrap the terrine in a loaf pan with heavy-duty foil or slip it into a large resealable plastic bag and freeze. To quickly soften frozen yogurt, beat in a stand mixer with paddle attachment until smooth.
Line a 9- x 5-inch (2 L) loaf pan with plastic wrap, leaving a 3-inch (8 cm) overhang. Arrange half of the strawberry slices in a snug single layer on bottom of pan to cover. Top with half of the strawberry frozen yogurt, spreading to smooth top. Sprinkle evenly with half each of the raspberries and pistachios; freeze until firm, at least 1 hour.
Top with layer of vanilla frozen yogurt, spreading to smooth top. Sprinkle evenly with remaining raspberries and pistachios; freeze until firm, at least 1 hour.
Top with remaining strawberry frozen yogurt, spreading to smooth top. Top with enough remaining strawberry slices to cover surface in snug single layer; cover with plastic wrap and freeze until firm enough to slice, about 2 hours.
To serve, turn terrine out onto serving plate, using edges of plastic wrap as 'handles;' remove plastic wrap. (If it doesn't release right away, let stand at room temperature just until it does, 2 or 3 minutes.) Using a large knife and running the blade under hot water between slices, slice into 1-inch (2.5 cm) slices. Garnish with mint leaves and additional berries, if desired.
Per serving (each of 10): 204 calories, 10 g protein, 5 g fat (2 g saturated fat), 29 g carbohydrates, 3 g fibre, 18 mg cholesterol, 66 mg sodium