You need to either create a slurry in a cold liquid, which also works with cornstarch, or you've got to do your gravy in a very wide pan and kind of scatter the flour over the top and then very quickly whisk it in.
Alton BrownI looked for a very long time, knowing that it had to happen, but it took me a long time to find someone with the same background and whatnot and I finally found him
Alton Brown