Tuck into a big bowl of mussels in under 30 minutes.
Prepare the mussels: check all the mussels are closed and discard any that are open or don’t close with a gentle tap, together with any that are cracked or damaged. Pull off the beard and scrub with a stiff brush under cold running water to remove any barnacles.
Heat the butter and oil in a large wide saucepan. Add the onion and garlic and cook gently for 2 minutes. Add the apple and cook for 1 minute. Add the apple juice, lemon zest and juice, and thyme, and bring to the boil.
Add the mussels, shake the saucepan a few times and cover with a lid. Cook for about 2 minutes, then shake the mussels again. Cook for another 6-8 minutes, until all mussels have opened.
Discard any unopened mussels and serve immediately, garnished with dill.