Brush off the mussels and remove the "beard" Rinse in water several times and let them drain. Discard shells that are broken and those that do not close when you poop them on the bench.
Peel and finely chop the garlic.Cut the spring onion into slices, save parts of the green part for garnish.
Divide lengthwise, remove the seeds and make strips of chili.
Place the lemongrass on the felt and tap it lightly with a saucepan so that the fibers divide, then tie a knot of the grass and hold it together.
Blanch garlic, spring onion and chili in oil in a large pot that has room for the shells.
Add coconut milk and lemongrass, bring to a boil.
Put the mussels in a saucepan and cook for 3-4 minutes under a lid, stirring gently a few times.
Take out the mussels with a slotted spoon and place in a bowl, discard those that have not opened.
Reduce the broth for a few minutes, season with pressed lime, salt and pepper.