Put 16 cups of water into a large saucepan and bring to a boil. Add 2 tablespoons of salt and the cauliflower florets and cook them until tender-crisp, about 5 to 8 minutes. Remove the cauliflower florets with a slotted spoon and plunge them straight into a bowl of iced water.
Pour out half of the boiling water and add the white wine vinegar, remaining salt, fennel seeds, and garlic cloves. Bring the pan back to a boil and add the celery, onions, peppers, fennel, and whole chiles; cook for about 10 minutes until tender. Refresh the vegetables in the same way, plunging them into iced water; when they are cold, drain them along with the cauliflower florets.
In a large bowl, mix the cauliflower and other vegetables with the garlic, olives and capers. Whisk together the vinegar and oil for the dressing and pour over the salad. Season with salt and pepper and sprinkle over the chopped parsley. Combine everything really well, which is easiest done using your hands. At this point you have a pickled vegetable salad which serves 8 generously, or you can stuff everything into wide-necked sterilized canning jars and pour in a mixture of half vinegar and half olive oil to cover the vegetables.
Recipe courtesy of Nigella Lawson