How to Make It
Line an 8-by-4-inch metal or glass loaf pan with plastic wrap, leaving a few inches of overhang all around. In a medium bowl, combine the yogurt, sugar, lemon zest, lemon juice and salt and whisk until smooth. Transfer to an ice cream maker and freeze according to the manufacturer’s instructions; the yogurt should be frozen but still spreadable.
Meanwhile, in a food processor, combine the mangoes, honey and cream and puree until smooth. Transfer half of the mango puree to a bowl and refrigerate.
Working quickly, spread one-third of the frozen yogurt in the prepared loaf pan in a 1/2-inch-thick layer. Gently spread half of the unrefrigerated mango puree on top and scatter with some of the blueberries and pistachios; gently push them into the puree. Repeat with another third of frozen yogurt and the remaining mango puree, blueberries and pistachios. Spread the remaining frozen yogurt on top. Cover and freeze the terrine until firm, at least 8 hours or for up to 5 days.
Carefully unmold the terrine onto a platter; peel off the plastic wrap. Cut the terrine into 1/2-inch-thick slices, rinsing the knife under hot water and drying it between cuts. Serve with the chilled mango puree.