Preheat the oven to full whack (240ºC). Pile the flour into a bowl with a small pinch of sea salt, add 80ml of water and mix into a dough, then knead on a flour-dusted surface for 2 minutes, adding a little extra flour, if needed. Roll and stretch out into a large oval (about 15cm x 30cm), then place in a large sturdy oiled tray. Cover with a clean damp tea towel and leave to rest while you put a small non-stick frying pan on a medium-high heat, then squeeze balls of sausagemeat out of the skins into the pan (if using veggie sausages, roughly slice and use 1 tablespoon of olive oil for frying). Fry until golden all over, tossing regularly, while you peel the red onion and slice super finely, ideally on a mandolin (use the guard!). Pick the rosemary leaves and toss with the onion, a pinch of sea salt and black pepper and 1 tablespoon of oil until well coated. Spread the tomato paste over the dough, sprinkle over the dressed red onion, and spoon over the sausage balls. Toss the grapes into the pan for 1 minute, then spoon over the pizza with any juices, tear over the mozzarella and sprinkle with the pine nuts. Place the tray over a high heat on the hob until it starts to sizzle, then cook at the bottom of the oven for 10 minutes, or until golden and crisp.