Roux is an odd one as that is butter (oil) and flour at a 1:1 to ratio cooked over heat until the desired color is reached. It's the key ingredient in gumbo whi

Roux is an odd one as that is butter (oil) and flour at a 1:1 to ratio cooked over heat until the desired color is reached. It's the key ingredient in gumbo which has been made since at least the early 1800s.