Pour enough oil into a large frying pan to cover the base and heat until shimmering. Fry the buns, prawn-side down, for 2-3 mins until golden and cooked through. Carefully transfer to a plate or board lined with kitchen paper to drain. Toss the coriander through the slaw, if using, then divide the slaw between half the buns and drizzle over sriracha or sweet chilli sauce, if you like. Sandwich the bun halves together, then serve.
