Making the strudels

1. Blanch the spinach leaves for a few seconds in boiling water to soften them;
2. clean and devein each langoustine;
3. wrap each langoustine or lobster tail in a spinach leaf;
4. brush two sheets of phyllo pastry with melted butter; place the langoustine on top; fold the sides over and roll up into quite a tight little roll; repeat for each langoustine;
5. heat a very small quantity of oil in a pan; brown the strudels on each side - the process should not take longer than about 15 seconds per side, so that the inside stays raw: the heat will radiate to the centre and cook the langoustines as you make the sauce.

Making the sauce

1. Finely chop the stems of lemon balm, the shallots and the ginger;
2. sauté very gently in a few drops of olive oil, not letting the mixture brown - otherwise the sauce will take on an unattractive colour;
3. pour in 60 ml of white wine and let it reduce;
4. pour in the rest of the white wine and let it reduce again;
5. add the cream; continue reducing until it takes on a slightly yellow colour - the sauce may be reduced by half or three-quarters, depending on whether you want a lighter or a creamier sauce;
6. gradually whisk in the butter, cut into dice;
7. season with salt and pepper; add a little lemon juice if you wish;
8. spoon a layer of sauce over the bottoms of a plate; place the strudels on top; garnish with a few lemon balm leaves and serve immediately.