Heat a large saucepan or Dutch oven over medium heat. Add the butter (or olive oil). Once melted and shimmering, add the diced onion, carrot and celery. Cook, stirring occasionally, until the vegetables are softened and the onion is translucent, about 6–8 minutes.

Add the minced garlic and fresh thyme and cook 30–45 seconds more until fragrant, taking care not to brown the garlic.

Pour in the chicken (or vegetable) stock and 1 cup water. Add the bay leaf. Increase heat to bring the mixture to a gentle simmer.

Main Vegetables & Protein

When the broth is simmering, add the diced potato. Simmer gently, uncovered, until the potato is nearly tender, about 10–12 minutes.

Add the diced zucchini, corn kernels and drained diced tomatoes. Return to a simmer and cook until all vegetables are tender, about 6–8 minutes more.

If using cooked shredded chicken, stir it in now and heat through for 2–3 minutes. Taste to ensure chicken is warmed.

Seasoning & Finish

Remove the bay leaf. Season the soup with kosher salt, freshly ground black pepper and red pepper flakes (if using). Stir in the fresh lemon juice and chopped parsley.

If you prefer a slightly thicker soup, use an immersion blender to purée 1–2 cups of the soup (or transfer a portion to a blender), then return to the pot and stir to combine. Adjust seasoning after blending.

Simmer another 1–2 minutes to let flavors marry, then remove from heat.

To Serve

Ladle the soup into bowls and garnish with croutons or toasted baguette slices and a light sprinkle of grated Parmesan if desired. Serve hot.