Minced beef and vegetable filo pie

Name: Minced beef and vegetable filo pie
Cuisine: European, British
Ingredients: 1 tsp rapeseed oil; 1 onion, diced; 100g mushrooms, chopped; 250g lean minced beef; 1 carrot, diced small; 150g sweet potato, peeled and diced into small pieces; 2 tsp plain flour; 1 tsp tomato puree; good pinch white pepper; pinch dried thyme; 1 reduced-salt beef stock cube, dissolved in 300ml water; 75g defrosted frozen peas; 2 sprays rapeseed oil; 150g filo pastry (approx. 3 sheets)