Add a glug of oil to a large casserole and fry the onions over a medium heat for 5-6 minutes, until they start to soften.
Add the ground spices and fry for a few minutes more, then add the garlic and ginger and fry for another couple of minutes, stirring.
Add the harissa paste, stir and fry for another few minutes until aromatic, then add the squash, parsnips and carrots. Turn down the heat and cook, stirring regularly, for 5-10 minutes.
Add the red lentils, tomatoes and stock, then season to taste. Bring up to a simmer and add the apricots.
Put the lid on the casserole and leave to simmer on a low heat for 50 minutes.
Remove the lid, stir in half the chopped parsley and check the seasoning.
Test if the vegetables are ready by piercing with the tip of round-bladed knife – if it goes in easily, they are ready.
Serve the tagine with warmed couscous, scattered with the remaining parsley.