1. Pre-heat the oven to 200 degrees C (400 deg F / gas mark 6). Peel and finely chop the onion, peel and crush the garlic.
2. Take the coriander (or parsley) and separate the leaves from the stalks. Roughly chop the leaves and set aside. Finely chop the stalks.
3. Finely chop the carrot and the mushroom to form dice no larger than 5mm.
4. Heat 1 tbsp of oil in a large frying pan and sweat the onions and chopped carrot for 5 mins or until the onion is translucent. Add the mince to the pan and cook until it is nicely browned.
5. Add the smoked paprika, garlic, chopped mushrooms and the finely chopped herb stalks; season with salt and a good grind of black pepper. Cook for a couple of minutes then add the passata (or chopped tomatoes).
6. Stir in the stock pot and add the water. Reduce the heat and cook for 15 mins or until the meat sauce has reduced by half, then add the chopped herb leaves and set to one side.
7. Whilst the meat sauce is simmering peel the sweet potatoes and cut into rounds 5mm thick. Also cut the courgettes into rounds 5mm thick.
8. To assemble the meal, take a deep baking oven dish (I use a deep pyrex dish which is about the size of an A4 sheet of paper) and place a layer (or two) of courgettes in the bottom and season.
9. Spoon over the meat sauce and top with the sliced sweet potato. Season with a pinch of salt and drizzle with a little oil.
10. Bake in the oven for about 25 minutes or until the sweet potato is cooked through.
11. Once baked, place the oven dish under a hot grill until the sweet potatoes go brown and crisp (take care not to overdo this bit!)
12. Serve and enjoy.