The kitchen is a great place to start when using bicarbonate of soda. Typically stainless steel can become stained or build up of limescale (depending on area). This can be quite hard to shift without using strong chemicals or abrasives, for that reason using a natural and kinder alternative may be better for your cleaning.
There are two methods effective with cleaning your kitchen sink.
Firstly, sprinkle the bicarbonate of soda over the sink. Using a light abrasive brush or pad scrub the sink and draining board then rinse.
If the stains or scale is stronger then you could sprinkle the bicarbonate of soda, then cover with kitchen paper and then spray the vinegar over the paper. Let this sit for 20 minutes and then remove the paper, lightly scrub and rinse the sink.