To prep the kale, remove the stems and chop the leaves into bite sized pieces. Place the chopped kale in a large salad bowl and sprinkle the leaves with a pinch of salt. With clean hands massage the kale leaves by scrunching it between your hands for about 1 minute. The kale will become darker in colour when you do this.
Cut the brussel sprouts in half and then finely shred them. Place the shredded brussel sprouts in the bowl with the kale and add in the chopped walnuts and bacon.
In a bowl whisk together all of the ingredients for the dressing until smooth and well combined. Taste and adjust the flavour if necessary by adding more mustard or lemon if necessary.
Pour the dressing over the salad and toss to ensure its evenly coated. Season with salt and pepper before serving.