Instructions: 

De-seed the chili pepper, put it in a blender along with cucumber, onions, coriander, lime juice and olive oil. 
Blend for a few seconds to roughly chop. 
Put the mixture in a bowl and add salt and pepper to taste. 
Clean the oysters under running cold water using a brush to get rid of grit and sand. 
Open the oysters and arrange on a large plate, then spoon the dressing on top. 

Tip: Prepare the dressing ahead of time and refrigerate. 

Recipe adapted from Riaboo, nibbledish.com