Spiced parsnip shepherd's pies

Name: Spiced parsnip shepherd's pies
Cook time: 1 h
Total time: 1 h
Cuisine: British
Ingredients: 2 tbsp sunflower oil; 1 large onion chopped; 2 garlic cloves crushed; small knob of ginger peeled and granted; 2 tbsp medium curry powder; 500g minced beef or lamb; 400g can chopped tomato; 100g frozen pea; 600g parsnip peeled and chopped into large chunks; large potato peeled and chopped into large chunks; 1 green chilli deseeded and chopped; large bunch coriander chopped; 2 tsp turmeric; juice of 1 lemon; 50g butter