● Preheat the oven to 180°C.

● Combine the carrots, celery, fennel, onions, garlic, courgettes, mushrooms, and parsnip in a large mixing bowl. Drizzle the olive oil over them and toss to coat evenly. Arrange the vegetables in a single layer on baking sheets and roast for 30 minutes in the centre of the oven.

● Rotate the veg on the pan and bake for another 30 to 40 minutes. They should be caramelised and brown, but not burnt.

● Transfer the vegetables to a large stockpot. Be sure to add all their juices as well, adding a small amount of water to the hot baking sheet to help loosen any bits that are stuck.

● Cover with 3 quarts of water and add the sea salt, peppercorns and bay leaves.

● Bring the broth to a boil and reduce to a simmer. Add the herbs and kombu. Simmer uncovered for 1 hour.

● Strain out and discard the solids.

● Divide into freezer-safe containers for storage, allow to cool and freeze for up to 3 months, or refrigerate and eat within 5 days.

Kombu is a form of dried seaweed used in Japanese cooking and available from health food stores or Japanese grocers