In a medium (4- to 5-quart [3.8- to 4.7-L]) pan, warm up 2 tablespoons of the olive oil.
Add the peppers and a sprinkling of salt and cook for 5-7 minutes, until the peppers soften.
In another medium (4- to 5-quart [3.8- to 4.7-L]) pan, warm up the remaining 3 tablespoons olive oil over medium heat.
Add the onions and ½ teaspoon salt and cook for 8-10 minutes, until the onions are translucent. Set aside.
Preheat the oven to 400 degrees F.
Punch down dough and halve.
Pat each half into an oval about 1/4 inch thick.
Transfer one oval to a lightly oiled large baking sheet. Layer with the tomatoes, onions and olives.
Cover with the second oval and press the edges to close the fougasse.
Score the top diagonally.
Layer the peppers on top, alternating the three colors for visual appeal.
Sprinkle with sea salt and the herbs.
Bake for 40-45 minutes, until the fougasse is golden.