Spring Onions: The gift that keeps on giving

I've had these spring onions for several months now.  They're a food you can regrow seemingly indefinitely from 'scraps'.  Just keep the stalks in water next to a window, and they'll regrow themselves to about half their original length every couple of weeks.  There's actually quite a few other edibles you can regrow - next experiment: broccoli - so far with no results perhaps because of the time of year, or maybe I'm just impatient - and it's a very satisfying thing to do.  A few tips I've learned from regrowing spring onions:

1.  Stalks should be about two inches long.  Occasionally you may need to peel off the outer layer.
2.  Refresh the water each time you cut the onions.
3.  Keep the water (and the roots) out of direct sunlight, in a cup rather a glass, as pictured.

It's interesting to speculate how it might be possible to live entirely off scraps of regrown food.  As with so many other things I've been learning about this year, I'm forced to ask myself: why aren't we all doing this?