No not sliced,, just chopped in to equal sized pieces,, by the looks of that bowl,, I think you done it,
The more you cook it gently the more the sauce reduces,, and the flavour intensifies ,,, you also don't want it to runny for a pie,,,you need a happy medium...
There's a few other vedges you can put in ,,,celery ,, turnip/ swede ,,,,but I prefer sweet potatoe instead of turnip,,
Looks nice that joe,,, did you follow my recipe ,, what did you think