What is exactly Avijja -- and how to uproot it?
Maybe you've heard of the old South Indian Monkey Trap (from this article):


  In Zen And The Art Of Motorcycle Maintenance, Robert Pirsig’s
  bonkers-but-brilliant philosophical novel that turns 40 this year, he
  describes “the old South Indian Monkey Trap”. ... The trap
  “consists of a hollowed-out coconut, chained to a stake. The coconut
  has some rice inside which can be grabbed through a small hole”. The
  monkey’s hand fits through the hole, but his clenched fist can’t fit
  back out. “The monkey is suddenly trapped.” But not by anything
  physical. He’s trapped by an idea, unable to see that a principle that
  served him well – “when you see rice, hold on tight!” – has become
  lethal.


The monkey needs to let go of the rice in order to free himself from his suffering. The way to end his suffering, is to end his craving for rice.

But in order to end his craving for rice, he must first understand how his hand is stuck inside the coconut. When the monkey overcomes his ignorance about how the trap works, he would let go of his craving for rice, and release his clenched fist. With this, he would be free from his suffering.

Also you can say that the monkey's suffering originated with his ignorance of the trap.

Knowing how the trap works, i.e. gaining insight and wisdom into the nature of reality, is the way to overcome ignorance.


(Illustration above: Paul Thurlby for the Guardian)