Take a pile of soft cooked, glutinous rice, pour it into a wooden mortar and pound the crap out of it with a mallet until you get a gooey, steaming mess. Form that into handful-sized balls and let it cool. There you have mochi.
An auspicious day is chosen right before the New Year and tons of the stuff is made and passed around among friends and relatives. It's also sold in stores and on street corners. Then for the next week or more, it's eaten at nearly every meal.
Let's see, you can cover it with sweetened red bean paste,
eat it in a red bean soup or even with strawberries.
If you want a non-sweet version, there is ozoni, a soup with boiled radish, Chinese cabbage, other veggie goodies and a square of mochi dropped into the middle.
You can also grill it with cheese and a drop of soy sauce or stick a square into a bowl of udon noodles.
Here's an idea of how exceptionally elastic it is.
I watched the movie Tampopo before I came to Japan and remember distinctly the scene with the old man who was so excited to eat mochi he inhaled it, choked, and had to have someone suck it out with a vaccuum. It was disturbing, funny and completely unreal; or so I thought. After I'd been here awhile, I learned that really happens. A lot.
This stuff is hot and gooey and very throat clogging if you don't chew it well. What really shocked me was that after the New Year's holidays our local newspaper keeps a running number of how many people have choked on mochi, who died and who was saved by a fast-thinking loved one with a vaccuum cleaner close by.