Heat 1 tablespoon of olive oil in a large pot over medium heat. Once hot, add the chopped onion and sauté for 3-4 minutes, stirring occasionally until it becomes soft and translucent.Next, add the chopped carrots and celery, cooking for another 5 minutes to release their natural sweetness and enhance the soup’s base flavor. Stir in the diced potatoes, ensuring they are evenly distributed. Pour in the 14.5 oz can of diced tomatoes, including the juices. This adds a rich depth of flavor and natural sweetness to the soup.
Pour in 4 cups of vegetable or chicken broth, stirring to combine all ingredients. Add 1 teaspoon of dried thyme, 1 bay leaf, and salt and pepper to taste. Bring the soup to a gentle boil, then reduce the heat to low and let it simmer uncovered for about 20 minutes, allowing the flavors to meld together.
Once the potatoes are tender, stir in the 1 cup of green beans (fresh or frozen). If you’d like to boost the nutrition, add 1 cup of spinach, kale, or peas at this stage. Let the soup simmer for another 10 minutes, allowing the vegetables to cook through while keeping their texture.
Remove the bay leaf and give the soup a final taste. Adjust the seasoning with more salt, pepper, or an extra dash of thyme if needed. If you prefer a slightly thicker consistency, you can mash some of the potatoes with a spoon or use an immersion blender for a few pulses.
Ladle the warm vegetable soup into bowls and serve with crusty bread, crackers, or a side salad. For extra flavor, garnish with fresh parsley, grated Parmesan, or a squeeze of lemon juice.