Peel or scrub the carrot. Halve lengthways. Thinly slice it. Thinly slice the celery. Peel and finely chop the onion. Peel, quarter and thinly slice all the beetroot. Peel and thinly slice the garlic.
Warm a large pan for 1 min over a medium heat. Add 1 tbsp oil. Add the carrot, celery, onion and beetroot to the pan. Add the bay leaves with a pinch of salt and pepper. Stir well to mix. Fry for 5 mins till the veg start to soften.
Add the garlic. Crumble in the stock cube, then pour in 800ml boiling water. Cover. Bring to the boil, then turn the heat down a little and simmer for 30 mins.
Finely grate the zest from the lemon and add to the soup with a squeeze of lemon juice. Taste and add more salt and pepper if you think it needs it. You can leave this soup chunky or ladle it into a blender and blitz to make a smooth version (discard the bay leaves before blitzing).