For the tart shell, combine the flour, cheese, and salt, and blend well. I process the cheese and flour together because I usually have sliced or grated Parmesan cheese.
Add just enough water so the cheese and flour stick together in a ball.
Now to place the dough in the tart shell. You can either roll the shell out between two pieces of parchment paper or another non-stick surface, or you can do what I usually do, which is mold the dough into the shell with my fingers.
Bake the shell at 350 degrees F for 10 minutes, or just before it begins to brown.
Cool the tart shell for a few minutes.
To caramelize the onions, place them in a frying pan with a pinch of salt and enough olive oil to coat them and the pan completely, and then some extra. Cook on a low to medium flame for about 15 minutes, or until they are clear and starting to turn sweet and a bit gooey.
To prepare the tomatoes, slice them and place them on parchment paper (or a non-stick mat), sprinkle lightly with salt and a light coat of olive oil (I spray oil over them), and bake at 325 degrees F for 15 minutes. Alternatively, you can heat them up a frying pan in the same way you caramelized the onions. You could even cook the tomatoes and onion together, but I like separating the flavors in the tart.
Layer the caramelized onions on the bottom of the tart shell, then the tomatoes, and then the goat cheese. Sprinkle the top with pine nuts, and bake the tart for 10 minutes at 350 degrees F, or until the edges are slightly browned.
This tart tastes great warm, or at room temperature, and is easy to store in the refrigerator and reheat. I reheat slices at 325 degrees F for 5 minutes. It goes great with a salad.