Heat your oven to 200°C/Fan 180°C/Gas 6. Trim the ends of the aubergine and courgettes. Chop the veg into 2 cm thick slices, then cut into cubes. Cut the tomatoes into quarters. Halve, peel and thickly slice the onion.
Peel and grate the garlic into a large bowl. Whisk with 1 tbsp oil and plenty of salt and pepper. Tumble all the veg into the bowl and toss together to coat the veg in the garlicky oil.
Tip the veg onto a baking tray and spread them out into a single layer. Slide it into the oven and roast for 30 mins. The veg should be charred and softened. Toss halfway through. Zest and juice half the lemon.
After the veg has cooked for 30 mins, place the pollock fillets on top of the veg, skin-side up. Crumble over the half pack of feta (see our tip below for what to do with the rest). Slide back into the oven and cook for 10 mins till the fish is just cooked through and the feta is golden. The fish will be white and flake easily when pressed with a fork.
Remove the tray from the oven. Divide the spinach between 2 plates. Drizzle with a little lemon juice. Spoon over the roasted veg and top with a piece of fish each. Scatter over the lemon zest and oregano leaves. Squeeze over wedges of the remaining lemon to taste.