Wash all the herbs in cold water and dry.Remove the stems from the green onions and discard them.
Lightly brush the chilli and green onions with a little vegetable oil. Season well with salt.
Grill the green onions and chilli over high heat until nicely charred but not too much (about 3-5 mins).
Let them cool on a tray for 5 minutes.
Blitz everything in the blender until a sauce is formed. Add salt to your liking.If preparing this sauce for later, leave the red wine vinegar out until you are ready to serve.
Serve the sauce at room temperature. If it's too thick, add a splash of cold water or more olive oil.
The red wine vinegar will discolour the sauce quickly so only add it when you're ready to eat the sauce. If you are making the sauce ahead of time, you can mix everything except the red wine vinegar and add this right before serving.