PASTRY: Put flour and salt in large mixing bowl. Using your fingertips or pastry cutter, rub butter into flour just until pea sized pieces of butter remain. Add 1/4 cup ice water and gently knead just enough for ingredients to hold together. If necessary, add a bit more water to help pastry stick together. Wrap in plastic and refrigerate until firm, about 1 hour. Divide pastry into 6 pieces. On lightly floured surface, roll each piece into a round about 1/8 inch thick. Cut each into a circle, about 5 1/2 inches in diameter. Place on parchment-lined cookie sheet; refrigerate at least 30 minutes. FILLING: Spread about 1/4 cup applesauce, nearly right to edges, over each pastry circle. Arrange apple slices, overlapping slightly, in a circle in applesauce. Brush apple with butter and sprinkle with sugar. Bake in a preheated 350F oven until apples are tender and underside of pastry is golden brown, about 1 hour. Heat jam with water over low heat. Strain through sieve over bowl. Brush over apples. Serve with ice cream or creme anglaise. MAKES: 6 TARTS