Preheat the oven to 180°C
Heat the olive oil in a large ovenproof saucepan or cast iron pot over medium heat.
Add the diced onion and saute for about 5 minutes until soft, turn your heat down if it starts to brown.
Add the five spices, carrot, potato, parsnip and sweet potato and stir, coating all the veggies in the spices. Continue cooking for a few minutes.
Add lemon juice, stock, pureed tomato and salt, stir in and bring everything to a boil.
Place the lid on the pot and move to the preheated oven for 45 minutes.
Check to see how tender the vegetables are after the 45 minutes, and that there is still enough liquid in the pot and then add the zucchini and chickpeas. Return to the oven for a further 10 minutes.
Take the tagine out the oven and add the spinach and stir in until just wilted.
Serve with lots of coriander sprinkled over the top, fresh flatbread on the side and a big dollop of harissa if you like a bit of extra heat.