Quarter the apples then cut away core and thinly slice. Add them to a medium bowl, douse them with a little lemon juice and add the onions and dill.
In a small pot over medium heat add the vinegar, bay leaves, peppercorns, salt and sugar. Stir and heat until the sugar has completely dissolved. Pour evenly over the apples and let stand 20 minutes, turning occasionally. Serve or cover and refrigerate until ready to use.