In a small saucepan over medium heat, melt the butter until foaming. Add the diced onion, carrot, and celery. Cook, stirring occasionally, until the vegetables are softened and the onion is translucent, about 5–6 minutes. Add the minced garlic and cook 30 seconds more until fragrant.

add flour

Sprinkle the flour over the softened vegetables and stir for 30–45 seconds to remove the raw flour taste; this will slightly thicken the broth.

add liquids

Slowly pour in the chicken or vegetable stock and the water while stirring to combine and prevent lumps. Bring the mixture to a gentle simmer.

Main Additions

cook potatoes

Add the cubed potato to the simmering broth along with the dried thyme and bay leaf. Simmer, uncovered, for about 8–10 minutes, until the potato pieces are nearly tender when pierced with a fork.

add zucchini and beans

Stir in the zucchini and the drained white beans. Continue to simmer for 3–4 minutes more until the zucchini is tender but not mushy and the beans are heated through.

finish with greens

Remove the pot from the heat and stir in the baby spinach; it will wilt quickly in the hot broth (about 30–60 seconds).

Seasoning & Finish

season and rest

Remove and discard the bay leaf. Season the soup with salt and black pepper; taste and adjust as needed. Stir in the lemon juice to brighten the flavors and fold in the chopped parsley.

Ladle the small soup into a single serving bowl. Serve hot, optionally with crusty bread or a small toast. Leftovers will keep refrigerated for up to 3 days.