Heat the olive oil in a large pot or Dutch oven over medium heat. Add the onion, carrots, celery, salt, and several grinds of pepper and cook, stirring occasionally, for 6 to 8 minutes, or until softened.

Stir in the garlic, then add the broth, thyme, orzo, and beans and simmer, uncovered, for 20 minutes, or until the orzo is tender.

Add the spinach and lemon juice and stir until the spinach is wilted. Season to taste and serve topped with freshly ground black pepper and fresh herbs, if desired.