As others have said – there’s nothing more needed than apples and the yeast, but both myself and the yeast like malted grain (probably for different reasons though :D ) so what I’ve done is used up some leftovers and made a small amount of beer wort to go with the ferment. Beer wort is loaded with all the nutrients yeast need to thrive, so it aids the ferment. One could use some yeast nutrient product as well, but this keeps it free of ‘additives’.

The syrup and sugar are really trace amounts in 23 liters, I add them to make the starter go brr. It’s just become a habit to have the syrup in there and I can’t leave it out now. Goes in all of my beer runs too :)