For the tart you need:
-Dough (I used puff pastry about 14 oz/400 g), the original recipe called for bread dough (about 14 oz/400 g) or you could simply use a quiche dough for a 10-inch tart. The puff pastry dough needs to be rolled out, line a lightly oiled 10-inch (25 cm) tart dish, pricked and refrigerated for about 30 minutes while you make the filling. The bread dough, if using, needs to stay out at room temp for 30 minutes once you have rolled it out and lined the oiled tart dish.
-Roll out the dough (even the puff pastry) so when you line the tart/pie dish the dough comes up the sides to make an edge just to the top of the dish.
For the filling you need:
-3 yellow onions – peeled, cut in half and thinly sliced
-2 cloves garlic chopped or minced (not too too finely)
-Fresh or dried thyme and basil (I used dried), salt and pepper
-About 6 medium (maybe 2 – 3 inches across) ripe tomatoes **
-A small handful tiny olives, such as Niçoise olives or Greek olives
-A bit of fresh goat cheese or feta, optional
** you can use about 400 g (14 oz) cherry tomatoes, sliced in half. Instead of brushing the cherry tomato halves with olive oil before baking, toss in 1 to 2 tablespoons olive oil before placing the halves in concentric circles, close together, on top of the caramelized onions.
-While the dough is resting, caramelize the thinly sliced onions in about 2 tablespoons olive oil. After about 5 minutes, when the onions become translucent and just start to color, add the garlic, salt and pepper and the herbs and continue to cook over medium or medium-low heat until the onions caramelized a golden brown. This usually takes about 10 minutes total. Remove from the heat and allow to cool for a few minutes.
-Preheat oven to 400°F (200°C).
-Spread the onions in the tart shell. If using goat cheese or feta crumble or lay slices over the onions, as much or as little as you like but only one thin layer. Cut off and discard the ends of the tomatoes and slice tomatoes about 1/4 inch thick and lay on top of onions/cheese in concentric circles, pressing the slices closely together in one tight, single layer. Lightly brush the top of each tomato with olive oil, salt and pepper again, a bit of basil and the olives, as many or as few as you like. Bake until the edges of the crust are golden brown about 30 minutes.
-Remove from the oven and allow to cool just a bit before serving in slices. This tart makes a wonderful meal with only a green salad, bread and a cheese platter and a bottle of wine.