Fall through mid-winter sunchokes consist mainly of inulin, a complex starch that humans CAN'T digest, but fart-making bacteria can eat just fine.

However, in late winter enzymes in sunchoke tubers begin breaking down the inulin into the simpler sugars the plant needs to grow...and that can also be digested as easily as potato starches. It's really quite fascinating, about the time the Native Americans had used up their winter stockpile of food and were facing starvation the sunchoke (aka Jerusalem artichoke) tubers suddenly were able to give them nourishment.

-Blast

edit: fixed to "humans CAN'T digest"