Heat the oil in a large frying pan or wok. Add the shallot and fry for 1-2 mins until softened. Add the garlic and celery seeds, and sizzle for 1 min more, then turn the heat up to high. Toss the prawns with the cornflour, cayenne and black pepper. Add to the pan and stir-fry for 1 min until turning pink, then add the vodka (stand back as it may catch fire) and bubble until most of the liquid has evaporated.
Add the passata, ketchup, Tabasco and a good pinch of salt. Give everything a stir and cook for 1 min more, then transfer to a serving dish. Scatter with celery leaves and place in the centre of the table with celery sticks and chunks of bread for mopping up the sauce.