To make the polenta crusted prawns:
Preheat the oven to 240°C/ gas mark 9. Line a baking sheet with foil.
In a small bowl combine the plain flour, sea salt and pepper. Into a second bowl break the eggs and whisk well. In a third bowl mix together the polenta, paprika and thyme.
Working in batches, dredge a few of the prawns in the plain flour, shaking off any excess. Holding the prawns by the tail, dip each one into the beaten eggs and then coat with the polenta mixture. Place the prawns on the prepared baking sheet and repeat to coat the remainder.
Drizzle the prawns with the oil and bake for 10-12 minutes, turning half way through cooking, until crisp and golden.
Sprinkle with extra salt and serve immediately with the mustard and herb mayonnaise.