Pulse together all crust ingredients in a food processor or beat with an electric mixer until a dough forms. Press dough evenly onto bottom and up side of tart pan with floured fingers. Chill shell until firm, about 30 minutes.
Preheat oven to 350°F (180°C).
Line shell with foil and fill with 1 inch of pie weights, raw rice, or raw beans; then bake in middle of oven until edge is pale golden, about 22 minutes. Carefully remove foil and bake shell until edge is golden and bottom is pale golden, about 20 minutes more. Cool completely in pan on a rack.
Reduce oven temperature to 300°F (150°C).
Mix together all custard ingredients in a bowl with a whisk (do not beat) until just combined. Set tart shell (in tart pan) in a shallow baking pan and pour three fourths of custard into shell. Carefully put tart in middle of oven and pour remaining custard into shell with a small cup.
Bake tart until just set in center, about 1 hour. Cool tart completely in tart pan on rack, then chill, covered, until cold, at least 2 hours. Just before serving, remove side of pan, and dust top of tart with confectioners' sugar.
Lemon juice may be substituted for the Lime juice in this recipe, if desired.
Tart shell can be baked 3 days ahead and kept, wrapped in plastic wrap, at cool room temperature. Tart can be chilled up to 2 days.
Makes 8 servings.
Source: Gourmet Magazine, December 2002
Date: October 5, 2003