Mushroom potato curry

Name: Mushroom & potato curry
Ingredients: 1 tbsp oil; 1 onion, roughly chopped; 1 large potato, chopped into small chunks; 1 aubergine, trimmed and chopped into chunks; 250g button mushrooms; 2-4 tbsp curry paste (depending on how hot you like it); 150ml vegetable stock; 400ml can reduced-fat coconut milk; chopped coriander, to serve