Wash the mussels in a few changes of cold water, scrubbing to remove any beards still attached to the shells. Discard any that are damaged, or opened ones that do not close when tapped. Drain off the water.
Heat the oil in a stockpot or large saucepan. Add the onion and garlic and fry for 5 minutes over a medium-low heat, stirring frequently, until translucent. Add the ginger and fry for a further 3 minutes. Do not let it brown.
Add the saffron, cider, stock, dill and some salt and pepper. Bring to the boil, add the mussels, then cover and cook for 4-5 minutes, shaking the pan occasionally, until the shells have opened.
Transfer the mussels ti serving bowls and discard any that remain closed. Stir the chopped parsley into the broth, spoon it into the bowls and serve with crusty bread.