I am not sure exactly what you are referring to… but if you start to cook (doesn't matter if you discard or burn it before it finishes) at least one dish every day, then you get bonuses.
These bonuses are (listed in not specific order - just an approx. guess)
day 1: random dish
day 2: random dish
day 3: $250
day 4: random dish
day 5: one toxin
day 6: random dish
day 7: $250
day 8: random dish
day 9: $250
day 10: three toxin's
…and it repeats.
This is not exactly what you get, I am having a guess… but it is roughly right. Approx four toxins gained every 10 days or so.
Don't forget to watch as many of those pesky videos each day that you can… that should gain you one toxin a day as well.
IMHO the best think you can do is to save your toxins up to get Granny Wolf (which needs 75) - it might take a while, but it is worth it. Don't bother spending toxins on anything else until you have all the Zombies you need. Once you have strong Zombies and can win most raids, then you will start to get more toxins for killing the head chef. This seems to be a random reward, but the quicker you get to kill the head chef then the greater the chance of getting those extra toxins the moment that he dies. I think I was on level 40 or so before it first started to happen… now it happens every few days! :)
