Sweet potato & lentil soup

Name: Sweet potato & lentil soup
Prep time: 10 min
Cook time: 25 min
Total time: 35 min
Cuisine: British
Ingredients: 2 tsp medium curry powder; 3 tbsp olive oil; 2 onions grated; 1 eating apple peeled, cored and grated; 3 garlic cloves crushed; 20g pack coriander stalks chopped; thumb-size piece fresh root ginger grated; 800g sweet potatoes; 1.2l low-sodium vegetable stock; 100g red lentils; 300ml milk; juice 1 lime