- Let the gumbo rest for a few minutes before serving to allow flavors to deepen. + Every 15 seconds or so precipitate will form in the roux, which you need to scrape off the bottom. A whisk is a pretty good tool for this. + If bits get stuck to the bottom, they will burn and the roux will be ruined, you can confirm this by tasting it. + The roux should be a dark brown color and have a nutty aroma. + In the beginning you can check for bubbles on the surface to indicate it's time to stir, but as the roux darkens that indicator is less prevalent.