Trim the very top and bottom off the leeks. Halve them and rinse out any grit. Finely slice them. Warm a pan for 1 min, then add ½ tbsp oil and the leeks. Season with a pinch of salt and pepper. Cover. Turn the heat down to low and sweat for 10 mins till the leeks are soft. Stir now and then.
While the leeks sweat, trim the ends off the celery and finely slice it. Peel the potatoes. Chop into chunks around 1½ cm wide. Peel and crush or grate the garlic.
Stir the celery, potatoes and garlic into the leeks. Crumble in the stock cube and pour in 700ml boiling water (or use hot homemade stock). Add 1 bay leaf. Cover, turn the heat up and bring to the boil. Lower the heat and simmer for 15 mins till the veg are tender.
Meanwhile, tip the almonds into a dry frying pan. Toast over a medium heat for 2-3 mins till golden, shaking the pan. Stir half into the soup. Fish out the bay leaf.
Taste the soup. Add more salt and pepper if it needs it. For a smoother soup, blitz in a blender or with a hand-held blender. Top with the remaining almonds.