Blanch the chives for 15 seconds in boiling water, refresh under cold running water and then pat dry. Place the chives into a liquidiser, pour in the oil and blitz until you get a really vibrant green colour: the longer you blend it, the more the colour will be enhanced. Season with salt and freshly ground pepper, and pour into a container and set aside.
Melt the butter in a large saucepan; add the onions and garlic and sauté to soften, then set aside.
Bring the stock to the boil, throw in
When ready to serve,