To make the tomato sauce, in a large, heavy frying pan over medium heat, warm the olive oil. Add the onions and saute for about 10 minutes. Do not allow to color. Add the tomatoes and cook, uncovered, stirring occasionally, until they have rendered their juice, about 15 minutes. Add the garlic, bouquet garni, and orange zest and season with salt. Stir one, reduce the heat to low, and simmer, uncovered, stirring occasionally, until the liquid is reduced by about one-third, 20- 30 minutes. Discard the bouquet garni and zest and season with salt and black pepper. If desired, add the cayenne and stir in the basil or parsley, if using. Set aside and cover to keep warm.