Ingredients: 10 Langoustines; 4 medium sized Leeks, trimmed; 2 tablespoons Olive Oil; 1 Vanilla Pod; 2 oz Butter; 50 ml Dark Rum; Salt & Pepper.
1. Chop the Leeks finely, and sweat in the Butter over medium heat until they have completely collapsed. (They shouldn't go to a mush, but should be not far off that). This might take half an hour or so. Season to taste once they are done.
2. Split the Langoustines lengthwise and arrange them, cut-side up, on a plate (or, more probably two, as you will almost certainly have to cook them in two batches). Mix the contents of the Vanilla Pod with the Oil, and brush the exposed flesh of the Langoustines with this mixture.
3. When the Leeks are practically done, cook the Langoustines for two minutes in the microwave on a high setting.
4. Heat the Rum gently in a small saucepan, then light it with a match and spoon the flaming Rum over the Langoustines, as the flames die down.
5. Divide the Leek mixture between five serving plates, and arrange two Langoustines on each plate. Spoon over any sauce that may have been left from the Langoustines plates.