Preheat the oven for the potatoes (electric cooker: 175 °C/circulating air: 150 °C/gas: level 3). Wash the potatoes, clean or peel the skin with a vegetable brush. Cut the potatoes into slices.
For the seasoning mix, mix 1 tablespoon paprika, 1⁄2 tsp cayenne pepper, 2 tsp sea salt and 1 tsp herbs of Provence. Mix 4 tablespoons oil, lemon juice and 1 tablespoon seasoning mixture. Add potatoes and mix. Bake on a baking tray in the oven for about 30 minutes.
Turning now and then.
Defrost frozen shrimps. For the dip, mix crème fraîche, ketchup and horseradish. Season to taste with salt and chilli. 3-4 minutes before the end of the baking time, drizzle the potatoes with the rest of the seasoning oil and turn.
Peel prawns, except for the tail fin. Make a longitudinal incision in the back and remove the dark intestine. Wash the shrimps and dab them dry. Peel garlic and chop very finely.
Heat 2 tablespoons of oil in a large frying pan. Fry the prawns and garlic for 3-4 minutes, turning them over. Season with salt and pepper. Serve with dip and potatoes.