Warm a splash of olive oil in a large pot over medium heat, then add the chopped onion and minced garlic; cook until softened and fragrant, about 3–4 minutes.

Add the chopped carrots and chopped celery to the pot and continue cooking until the carrots begin to soften, about 5 minutes.

Stir in the chopped zucchini and the 2 cups of mixed vegetables, cooking for another 2–3 minutes so they start to warm through.

Pour the 4 cups of vegetable broth into the pot and increase the heat until the liquid comes to a gentle boil.

Reduce the heat to a simmer and cook for about 15 minutes, allowing all the vegetables to become tender and the flavors to meld.

Remove the pot from the heat and stir in 1 cup of heavy cream or coconut milk until fully incorporated and the soup looks silky.

Taste and season with salt and pepper to your preference.

Ladle the soup into bowls and serve hot, garnished with fresh herbs if desired.