In a large heavy-bottomed pot or Dutch oven, heat butter and olive oil over medium heat until butter is melted and foaming. Add the diced onion, carrot, and celery. Season lightly with a pinch of salt. Cook, stirring occasionally, 6–8 minutes until the vegetables are softened and the onions are translucent but not browned.

add garlic

Add the minced garlic and cook 30–45 seconds, stirring, until fragrant.

Vegetables & Add-ins

build vegetable base

Add the diced potato, zucchini, and sliced mushrooms to the pot. Stir to combine and cook 3–4 minutes to begin tenderizing the vegetables.

deglaze (optional)

If using, pour in the white wine to deglaze the pan, scraping up any browned bits from the bottom. Let the wine reduce by about half, 1–2 minutes.

add tomatoes and spinach

Stir in the canned diced tomatoes with their juices and the chopped spinach. Cook until the spinach wilts, about 2 minutes.

Liquids & Stock

add stock and simmer

Pour in the chicken or vegetable stock and the additional cup of water. Add the bay leaf and thyme sprigs. Increase heat to bring to a gentle boil, then reduce heat to maintain a simmer. Partially cover and simmer 15–20 minutes, until the potato and other vegetables are tender when pierced with a fork.

Herbs, Seasoning & Finish

season and finish

Remove and discard the bay leaf and thyme stems. Stir in dried oregano, kosher salt, and black pepper. Taste and adjust seasoning. If you want a silkier, slightly richer soup, stir in the heavy cream or half-and-half and warm through (do not boil after adding cream). Add the lemon juice and most of the chopped parsley, reserving a little for garnish.

optional puree

For a creamier texture, remove about 2 cups of soup and puree in a blender until smooth, then return to the pot and stir to combine. Alternatively, use an immersion blender to partially puree directly in the pot, leaving some chunks for texture.

finish and serve

Stir in grated Parmesan if using. Ladle soup into bowls, garnish with remaining parsley and freshly ground black pepper. Serve with crusty bread or crostini.