Heat a large pot over low-medium heat. Once hot, add the oil and onion. Cook for about ten minutes, stirring frequently, until softened and lightly golden around the edges.
2 teaspoons oil, 1 medium onion
Add the potatoes, celeriac, broth, salt, and pepper. Stir to combine. Cover and increase the heat to bring the soup to a boil. Reduce the heat and simmer, covered, for about ten minutes or until the vegetables are soft.
300 grams floury potatoes, 200 grams celeriac (peeled) or parsnips, 750 ml vegetable broth, 1 teaspoon sea salt, ½ teaspoon black pepper
Turn off the heat and add the wild garlic. Blend with an immersion blender until very smooth. Add the lemon zest and juice, taste for seasoning, and serve hot.
250 grams wild garlic, Zest of a lemon, Juice of a lemon
Wild garlic soup can be kept in the refrigerator for up to three days and freezes well.