Heat a large soup pot over medium heat. Add the garlic and 2 tbsp of the oil, and wait for the garlic to cook, maybe a minute.
Add the onions, and cook until translucent, de-glazing with a splash of white wine if needed.
Add the celery, onion, parsnip, potato and the rest of the cooking oil, mixing well to coat all ingredients. Continue to cook over medium heat until potatoes are fork tender, about 10-15 minutes, stirring occasionally. As you continue to cook, ingredients will start sticking to the bottom of the pan, and as they do, continue to de-glaze with the white wine.
Once potatoes are fork tender, dust the flour over all ingredients, then stir well to incorporate. Continue cooking until flour at the bottom of the pan starts to brown, 3-4 minutes. Add vegetable stock in ½ cup increments, stirring well each time to prevent lumps.
Once all stock has been incorporated, continue to cook for a few more minutes, then remove from heat and cover. Serve immediately, or allow to sit for a few more minutes if you want it a little thicker.
Serve garnished with plenty of fresh parsley, croutons, and a drizzle of extra virgin olive oil.