I decided to use the microwave method because I am impatient. Here is my yarn about half-way through. I think it would go well with a marinara or Bolognese sauce.
I didn't think it looked very yellow, but the water was clear after 4 passes through the microwave.
And when I looked at it later, it definitely was yellow.
Unfortunately, I still haven't decided what I want to do with it! Maybe some mittens? And a hat?