The colour Mustard yellow is just like the spice. If you use too much, it'll ruin everything, but if you add just the right amount, it'll add flavour or in other words be spot on. A glorious accent!
Pair the mustard with an offwhite neutral and you'll keep your bathroom feeling light and breezy. To add a little moodiness and depth just add the colour charcoal, think accessories and floor tiles.
Then to finish it off and bring it all together, use some natural textures, such as timber and jute.