Easy vegan slaw

• ¼ white cabbage
  (roughly 200g), finely sliced
• ¼ red cabbage
  (roughly 200g), finely sliced
• 2 medium carrots
  (roughly 200g), grated
• ½ red onion
  finely sliced

For the dressing

• 2 tbsp lemon juice
• 2 tsp good quality Dijon mustard
• 4 tbsp extra virgin olive oil
  or rapeseed oil