In a large heavy-bottomed pot or Dutch oven, heat olive oil and butter over medium heat until butter melts and foams. Add the chopped onion, diced carrot, and diced celery. Cook, stirring occasionally, until the onion is translucent and the vegetables have softened, about 6–8 minutes.

Add garlic and flour

Add the minced garlic and cook for 30–45 seconds until fragrant. Sprinkle the all-purpose flour over the vegetables and stir constantly for 1–2 minutes to cook the raw flour taste and create a light roux.

Deglaze and add liquids

Slowly whisk in the chicken or vegetable stock and water, scraping any browned bits from the bottom. Add the bay leaf, dried thyme, salt, and black pepper. Bring mixture to a gentle simmer.

Vegetables & Proteins

Cook potatoes

Add the diced potatoes to the simmering broth. Cook for 10 minutes to begin softening.

Add remaining vegetables and tomato

Stir in the diced zucchini, frozen peas, and canned diced tomatoes with their juices. Continue simmering gently until the potatoes are tender when pierced with a fork, about 8–10 more minutes.

Add protein

If using cooked shredded chicken, stir it into the soup now and heat through for 3–4 minutes. Taste and adjust seasoning with additional salt and pepper as needed.

Finish & Garnish

Enrich and balance

If you want a creamier soup, stir in the heavy cream or half-and-half and warm gently but do not boil. Add lemon juice to brighten flavors and stir in grated Parmesan if using. If you prefer a lighter soup, skip the cream and just add the lemon juice.

Serve

Remove and discard the bay leaf. Ladle soup into bowls, sprinkle with chopped fresh parsley and a pinch of red pepper flakes if desired. Serve hot with crusty bread or crackers.