Combine shredded cabbage and carrots in a large bowl. Pour 4 cups of cold water over the mixture and add two tablespoons of salt. Soak cabbage mixture for 1 hour.
Dressing
Whisk together mayonnaise, mustard, lemon juice and lemon zest. Set aside
Making The Slaw
Drain cabbage mixture well and pat dry. Be sure to remove as much moisture as possible.
Pour the dressing over the cabbage mixture and combine well. Store in the fridge for 30 minutes.