Combine vegetable broth, potatoes, salt, oregano, parsley, cilantro, and pepper in a saucepan over medium-high heat. Bring to a boil; cook until potatoes start to soften, about 5 minutes. Stir in garlic. Add red bell pepper, onion, leek, carrot, and celery; simmer until potatoes are very tender when pierced with a fork, about 10 minutes more.