The persist creature does not have a -1/-1 counter on it.
You control your commander.
Steps
Activate Altar of Dementia by sacrificing the persist creature.
When the persist creature dies, it triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to your commander's ability granted to it by Master Chef.
Resolve the Altar of Dementia ability, causing target player to mill cards equal to the persist creature's power.