Put the carrots in a blender and pulse into small pieces (not too fine as you need to keep some texture). Transfer to a bowl, add the onion and mix together well.
To make the dressing, whisk together the lemon juice, oil, salt, sugar, white pepper, ginger and cardamom. Add to the carrots and onion, toss well and then leave in the cold for a few hours. Toss through a few mint leaves befo