Heat the rapeseed oil in a saucepan over a medium heat and fry the onions until they start to turn translucent. Add the garlic and cook for another 2 minutes, then add the minced beef and cook until it has started to brown.

Add the carrots, peppers, courgettes and mushrooms to the pan along with the tomato purée, tinned tomatoes, mustard and vinegar. Give everything a good stir, cover the saucepan with a lid and simmer for 20 minutes until the carrots are soft enough to squash between your thumb and forefinger.

Add in the chopped spinach and kales along wit the thyme then season with pepper.

Take the lid off the saucepan and continue to simmer for a further 10 minutes to allow the sauce to thicken.

While the meat sauce is cooking, place the potatoes in a pot of boiling water and cook for about 20 minutes, until they are soft through, then drain.

Add the butter and pepper then mash until smooth.

Place the meat mixture into a pie dish then top with the mashed potato. If freezing you can do so now. Otherwise, pre-heat your oven to 180ºC and cook for 30 minutes until golden brown and warmed the entire way through.

Serve warm.