Preheat the oven to 450°.
Heat onion slices and 3 tablespoons of olive oil on the stove in a medium-low pan until soft and caramelized, approximately 20 minutes.
Roll the puff pastry dough to 10 inches by 15 inches and place on a 10-inch-by-15-inch jellyroll pan. Two inches from the border, score the dough with a knife. Use a fork to dock, or poke holes, inside the border.
Layer goat cheese to the score line, but not over. In the same manner layer the Havarti cheese, caramelized onions, then okra and tomatoes. Brush the remaining olive oil around the edges of the dough. Sprinkle sea salt and cracked pepper over the tart.
Bake 15 minutes or until the crust has puffed up and browned, and the vegetables are cooked through.