Works on an even number of stitches.
Row 1: *Yarn over, slip 1, knit 1. Repeat from * across.
Row 2: *Yarn over, slip 1, knit 2 together. Repeat from * across.
Repeat only row 2 for pattern. Note that with the preparation row you'll be working on more stitches than you cast on, so plan for that when determining gauge.
When ending a project or area of ribbing that includes Brioche Stitch at the hem or cuff of a garment, work the row by eliminating the yarn overs and simply purling 1 and knitting 2 together across. After that row you can bind off in a regular knit 1, purl 1 ribbing pattern. Make sure you bind off loosely, as this fabric is very stretchy.
Note: slip stitches as if to purl with yarn in back.