Using the coarse holes of a grater, shred the cold butter or margarine. Toss with flour as you go, to coat the shreds. When the fat is in coarse chunks, fluff the mixture with a fork as you drizzle in the ice water. Use your hands to mix, pressing the dough together lightly. If it doesn't form a dough, sprinkle in water a teaspoon at a time. Gather the dough into a ball, form a disk, and wrap in plastic wrap. Refrigerate for at least 2 hours.
Preheat the oven to 400 degrees. Line a rimless baking sheet with parchment paper and reserve.
Sprinkle a little flour on the counter and roll out the dough to a 14-inch round. Place on the prepared pan. Cover a 12-inch circle in the center with the shredded cheese, and sprinkle with rosemary. Arrange the smoked tomatoes, cut side up, on the tart. Sprinkle with a pinch of salt. Fold 2 inches of the outside edge of dough over the filling to form a rim.
Bake for 30 to 35 minutes, until the pastry is crisp. Cool on a rack for 5 minutes, then slide the tart onto a large board or platter. Cut in 8 wedges. Serve sprinkled with basil.
Nutrition information per serving:
Calories220Fat13 gSodium500 mg