Char sweet frying pepper over open flame on stovetop or under hot broiler with oven door cracked to allow steam to escape. Once the skin is evenly charred and blackened all-over, place the pepper in a bowl and cover with plastic until pepper is cool enough to handle. Wipe or scrape the char off the pepper removing the skins. Seed the pepper and thinly slice.
Heat 3 tablespoons extra-virgin olive oil in a deep skillet or Dutch oven over medium to medium-high heat. When the oil ripples, add the zucchini, chiles, frying peppers, onions, potatoes, garlic, salt, pepper, rosemary, thyme and saute the vegetables until tender-crisp, 12 to 15 minutes, stirring occasionally. Add the tomatoes and roasted peppers and allow the tomatoes to breakdown a few minutes. Stir in enough stock to desired consistency - as thin or thick as you like.
Cool completely and store for make-ahead meal.
Reheat over moderate heat, stirring occasionally. Serve in shallow bowls with shredded or torn sweet basil and crusty, warm bread.