Heat is not the problem. I don't think you understand what browning onions well means. Which is understandable, because getting them "brown" in a few minutes is

Heat is not the problem. I don't think you understand what browning onions well means. Which is understandable, because getting them "brown" in a few minutes is pretty easy, and that's the way it's explained in most recipes. Browning usually means at least partial (noticeable in taste) caramelizing. That just won't happen in five minutes.