To make the caramel sauce, add the sugar and water to a heavy bottom sauce pan on medium low heat. Allow the sugar to dissolve and then raise the heat to medium. Continue cooking for a few minutes until it starts to take on a light amber color but do not walk away because it can burn quickly.
Pour in the heavy cream (the mixture will bubble up) and add the butter. Continue cooking and stirring until any lumps have dissolved and the mixture is smooth. Stir in the vanilla, tahini and sea salt.
To make the tart, pre-heat the oven to 400 degrees.
Toss the sliced apples in a bowl with the sugar, lemon juice, cinnamon and salt and let sit for about 5 minutes.
Gently roll out the sheet of puff pastry just to remove any creases but do not flatten it too much or it won’t puff. Drain the liquid from the apple mixture and pile them in the center of the dough. Fold the edges over to form a circle.
Brush the edges with the cream and sprinkle with the teaspoon of sugar. Bake at 400 degrees for 15 minutes, then lower the heat to 350 and bake for an additional 15 minutes or until the pastry is lightly golden brown.
Dust with powdered sugar and pour on the caramel sauce to serve.