In a large pot heat the oil, add the onion, garlic, leek and celery and cook for 2-3 minutes until softened, stirring frequently.
Add the zucchinis, potatoes, tarragon, stock (approx. ⅔), stir, cover and bring to the boil.
Lower the heat and simmer for about 20 minutes stirring occasionally.
Remove from the heat and puree. Top up with more stock if needed, adjust the seasoning and serve.
I recommend using medium size zucchinis as very large ones can sometimes be too bland.
Potatoes: Use all-rounders such as russets or Yukon Gold, Maris Piper or King Edward potatoes.
My choice of herb was tarragon, which has a sweetish kind of, slightly aniseed like, flavour, really lifting the subtle, timid zucchini. Zucchinis, however, pair well with virtually all herbs so use your favourite. You could also omit the herbs altogether.
Use hot stock to bring the soup to the boil quickly. You may need a little less or more stock than the recommended amount depending on personal preference so add a little less to start with.
For a non-vegan option serve with a knob of butter or sprinkle with a bit of cheese such as parmesan or another strong cheese. Scatter over lightly toasted seeds or croutons for crunch.
Best served immediately. Keep refrigerated for up to 3 days.
Freeze individual portions in airtight containers for up to 3 months.