The technique
Method
1
Melt the butter (or other fat) in a heavy-bottomed pan over medium heat.
2
Whisk in an equal weight of flour until smooth - you want a thick paste, not a batter.
3
Keep whisking over medium heat. For a white roux, cook 2-3 minutes; for blond, 5-7 minutes until pale gold; for brown, 15-20 minutes until it smells nutty.
4
Whisk in your liquid gradually, a splash at a time at first, to avoid lumps.
5
Bring to a simmer, whisking, until it thickens - a roux keeps thickening as it cooks.
Equal parts fat and flour, cooked together, is the base for countless sauces and soups - from a bechamel to a gumbo. The only variable is how far you cook it.
By Alistair Crawford