Wash the potatoes thoroughly. Dry them and cut them into cubes. Set aside in a bowl.
Preheat the oven to 180°C/Gas 4.
Mix together the juice of half a lemon, olive oil, the peeled and finely chopped ginger and the crushed garlic.
Cut the onion into quarters and add them to the potatoes and marinade, season with salt and pepper. Mix together then spread on a baking tray lined with baking paper. Cook in the oven for 30 minutes.
Add the shrimps to the potatoes. Mix everything together and cook in the oven for a further 10 minutes.
