1. Preheat the oven to 220°C, gas mark 7. To make the oven chips, cut the potatoes (but don’t peel them first) into long chips. Place in a bowl of cold water and rinse well then pat dry with a clean tea towel. Spread on a large baking tray in a single layer and drizzle with the rapeseed oil. Toss well and place in the oven to roast for 25-30 minutes turning now and then until golden brown, crisp, and soft in the centre.
2. Meanwhile, place the flour in a shallow bowl and mix in the cayenne pepper. Crack the egg into another shallow bowl and beat, and finally put the panko breadcrumbs into another shallow bowl.
3. Toss the prawns in the flour until evenly coated. Next, dip the prawns in the beaten egg and finally press them into the panko breadcrumbs. Repeat until you have coated all the prawns.
4. Heat the rapeseed oil in a frying pan and gently cook the prawns for about 2-3 minutes each side until golden, crispy and cooked through.
5. To make the tartar sauce, place all the ingredients in a bowl and gently mix together seasoning with a pinch of salt and ground black pepper. Spoon into a serving bowl.
6. Serve the prawns with the oven chips and tartar sauce and some minted peas and wedges of lemon to squeeze over.