Carrot, Parsnip and Beetroot Cupcakes

Ingredients

• 2 1/2 cups self-raising flour
• 1 1/2 cups brown sugar
• 1 parsnip, peeled and grated
• 1 carrot, peeled and grated
• 1 medium beetroot, peeled and grated
• 1/2 cup coarsely chopped walnuts
• Rind and juice from 1 orange
• 1 1/2 tsp mixed spice
• 1/2 cup vegetable oil
• 4 eggs, lightly whisked
• 300g sour cream