Heat your oven to 200°C/Fan 180°C/Gas 6. Halve your squash. Scoop out the seeds. Slice the squash into wedges around 2 cm thick. Arrange them, skin side down, on a baking tray. Season with salt and pepper. Bake for 35-40 mins till tender.
Peel and grate or crush the garlic. Halve the chilli and scoop out the seeds and white bits. Finely chop the chilli. Finely grate or pare the zest from the lemon. Juice it.
Pop the garlic, chilli, lemon zest and juice in a small pan with a pinch of the harissa. Gently heat for 1-2 mins till the pan smells spicy and aromatic.
Add the tinned cherry tomatoes to the pan. Add 1 bay leaf. Pop on the lid. Simmer for 10-15 mins till the sauce has thickened. Stir it every so often, lightly crushing the tomatoes against the side of the pan. Taste and adjust the seasoning.
Line a baking tray with baking paper. Pop the salmon fillets on the tray, skin side down. Season with a little pepper. Bake for 10-15 mins on the shelf above the squash (move the squash down a shelf) till opaque and cooked through.
While the salmon and squash cook, halve the cabbage. Slice out the thick middle core from one half. Finely shred that half and rinse it. Fill the kettle and boil it.
Fill a pan with hot water from the kettle. Bring to the boil. Add the shredded cabbage. Simmer, without the lid on, for 3-5 mins till the cabbage is tender but not too soft. Drain well. Serve with the salmon, the squash wedges and the harissa sauce.