1 tablespoon olive oil or butter
1 medium onion, chopped
2 carrots, diced
2 celery stalks, diced
4 cups vegetable broth or chicken broth
2 cups frozen or fresh green peas
1 cup diced potatoes (optional, for extra heartiness)
1/2 teaspoon dried thyme or marjoram (optional)
1/2 teaspoon salt, or to taste
1/4 teaspoon black pepper
Optional garnishes: chopped fresh parsley, crusty bread
Sauté aromatics and vegetables: Heat the olive oil or butter in a large pot or Dutch oven over medium heat. Add the chopped onion and cook until softened, about 5 minutes. Add the diced carrots and celery and cook for another 3-5 minutes.
Add broth, peas, and potatoes (if using): Add the vegetable or chicken broth, green peas, and diced potatoes (if using) to the pot. If using dried herbs, add them now as well. Bring to a boil, then reduce heat to low, cover, and simmer for 15-20 minutes, or until the potatoes (if using) are tender and the peas are cooked through.
Season and serve: Season with salt and pepper to taste. Ladle the soup into bowls and garnish with chopped fresh parsley and serve with crusty bread, if desired.