This is one of my favorite grocery multipliers because it takes a food that we eat a lot of – green onions – that is fairly high value and doubles or triples it for us.
You just need to save the part of the green onion that you ordinarily wouldn’t care to eat anyway – the very bottom root segment, about an inch up from the roots. When you cut up your green onions, just put this bit in some water and over the course of several weeks, it will sprout into some new green onions for you!
This trick won’t keep working forever. The additional green onion that is grown from the root tip gets much of its energy from the root tip itself, where many of the carbohydrates are stored. If you want to do this for an entire season – you’ll want to plant it in some actual soil.
Fortunately, that can be done in a mason jar too! You’ll just want to make sure to give your little plant some drainage, perhaps by filling the bottom couple inches with pebbles before adding the soil on top.