Broccoli & Celery Soup

Name: Broccoli & Celery Soup
Prep time: 5 min
Cook time: 25 min
Total time: 30 min
Cuisine: American
Ingredients: 2 tablespoons olive oil; 1 Large Onion (, 1 cup minced); 3 Celery Stalks (, 2 cups diced); 1 Large Head Broccoli ((1 pound/450 grams), see note 1); 2 cups Vegetable Broth (, see note 2); 1 cup Water; 2 teaspoons Salt; A Pinch of black pepper (, generous); Croutons (, optional)