Space food.

To be fair, the food the rest of us eat now (frozen microwave curry) is hardly on a par with what it was when Yuri Gagarin went into space.

As far as bioregeneration goes, I'd have thought that a tank that processes human waste and turns it into food using a collection of microbes would be a lot easier to implement. The microbes could be selected to also remove CO2 from the air, produce O2, and hopefully not produce too many other gasses.

Of course adding in some yeast to provide alcohol wouldn't go a miss too.