In a medium-sized mixing bowl, use a fork to combine flour, sugar, and sea salt. Use a box grater to grate in the butter and then rub into flour mixture with fingertips. Fold in just enough ice water so mixture holds together. Turn out onto a lightly floured surface, gather into a disc, and wrap tightly with plastic wrap. Chill in the fridge 30 minutes or longer.

Preheat oven to 375 degrees F. Set out a 14 x 5-inch tart pan (or the tart pan of your choice). 

On a lightly floured surface, roll chilled dough out into a 16 x 7-inch rectangle. Transfer to tart pan. Press into place and cut off all but a 1-inch overhang, and then fold overhanging dough into the sides of the tart, pressing to incorporate. Poke crust all over with the tines of a fork.

If time allows, set tart crust in the freezer to chill 10 minutes – this helps it retain its shape during the blind bake.

Set crust on a rimmed baking sheet. Line the inside of crust with foil and add pie weights, dried beans, or rice. Bake crust with pie weights for 12 minutes. Carefully remove weights and foil lining. Bake another 12 - 15 minutes, until shell is light golden brown. Set crust aside to cool completely before filling.

To make filling, stir to combine mascarpone, yogurt, 1/4 cup honey, lemon zest, 1 tablespoon lemon juice, and a tiny pinch of sea salt. In another bowl, combine remaining lemon juice, 2 tablespoons honey, and minced tarragon. Gently fold in fruit, taking care that it doesn’t bruise.

Spread mascarpone filling in cooled tart shell, arrange fruit on top, and garnish with reserved sprigs of tarragon. Set in fridge and chill 60 minutes.

Tart is best served day-of but will keep covered in the fridge for two days.