Start by preparing all the vegetables.
In a large saucepan heat up oil and butter (if using) and add cleaned and sliced leeks. Sauté them until they start to go soft but not too coloured (approx. 5-8 minutes). Give them a stir from time to time and a splash of water/stock if they start getting dry to help them along.
200 g leek (both green and white part), 1 tablespoon olive oil/oil of choice, 1 tablespoon plant or dairy butter
Add chopped garlic, thyme and bay leaf. Stir them in and cook together for another minute or so.
2 garlic cloves, 1 bay leaf, 1 teaspoon fresh or dried thyme leaves
Next, add chopped cauliflower, potatoes and enough stock to cover all the vegetables. Cover and bring to boil, then reduce the heat and simmer (semi covered) until all vegetables are tender.
450 g small head cauliflower, 500 g potatoes, 1.1 ltr vegetable stock
Blend the soup to desired consistency, taste and season with salt and pepper. The amount of salt needed will depend on the saltiness of your stock.
salt and pepper to taste
Optional: Add a good heaped teaspoon (or to taste) of your favourite mustard and either stir it in or give the soup another quick blend (especially if using wholegrain mustard). It adds extra flavour dimension to the soup.
1 teaspoon (heaped) your favourite mustard
Serve and enjoy!