Method:
1. Preheat the oven to 200 °C (for a convection oven, slightly higher for a regular oven).
2. Slice the lemon in half and place both halves flat side down in a frying pan on high heat. Leave for about 10 minutes (the flat side of the lemon should then be dark around the edges).
3. Crumble fresh yeast on a tray covered with baking paper and bake in the oven for about 15 minutes, until the yeast gets a deep golden colour. Remove from oven and cool on the counter before chopping roughly.
4. Add the butter, salt, thyme, juice from the grilled lemon, and yeast into a blender. Blitz until well blended. If you don't have a blender, you can mix the ingredients together by hand.
5. Slice the langoustines in half lengthwise. It's best to use fresh, raw langoustines. Arrange the langoustines in a rectangular baking dish, spreading a little of the butter mixture on each tail.
6. Bake in the oven at 200 °C for about 5-7 min (depending on the size of the langoustines). Play close attention so that they do not get overcooked.
7. Serve with freshly baked sourdough bread or white bread, and grilled lemon that you can squeeze on top.
This recipe can also be served as part of a larger meal or as an appetizer. Enjoy!