Mufaletta refers to both the sandwich and the style of bread that originated in Sicily. The sandwich itself comprises several deli meats, cheeses and an olive salad/spread and was created at a deli/café in New Orleans in 1906 to feed Italian immigrants.
Top and tail any of your veggies that need it. Dice the veggies - you want 1cm (just under half an inch) pieces. Keep the different types of veggies separate as you cut them because they may need to be cooked for different lengths of time. Bring the water and vinegar to the boil. Add the salt, sugar, bay leaves and the mustard, coriander and fennel seeds. Cook the carrots, green beans and cauliflower for 2 minutes, then add the celery, onion and peppers and cook for another 1-2 minutes. Place the veggies in a jar and top up with strained cooking liquid.
Mix the flour, salt, sugar and yeast together. Gradually mix in the water. Knead the dough for 10 minutes on a floured worktop or in a stand mixer with a dough hook. Transfer to a clean bowl, coat the dough with olive oil, cover the bowl with plastic film or a clean tea towel and leave in a warm place for the dough to double in volume, about 1½-2 hours.
Line a baking sheet with greaseproof paper and sprinkle with polenta or coarse semolina. Remove the dough from the bowl and punch all the air out of it. Form it into a ball and place it in the centre of the baking sheet. Splash with water and sprinkle with sesame seeds. Cover the sheet with a clean tea towel and leave in a warm place to prove again.
To bake the loaf, use a fan/convection oven or airfryer set to 200°C (392°F), 220°C (425°F) conventional or gas 7 for the first 10 minutes then lower the temperature to 180°C (356°F) for a fan/convection oven or airfryer, 200°C (392°F) conventional, gas 6 and bake for another 15 minutes. Allow to cool on a wire rack before slicing.
Polenta or coarse semolina for dusting