Heat the olive oil in a wide, heavy-based pot. Add the onion and cook until soft and golden, about 6–8 minutes.
Stir in the garlic and cook another minute until fragrant.
Add the crushed tomatoes, tomato paste, cinnamon (if using), salt, and pepper. Simmer for 10 minutes until slightly thickened.
Add the beans and water. Stir well to coat the beans in the sauce.
Cover and cook over low heat for 40–50 minutes, stirring occasionally, until the beans are very tender and the sauce has reduced. Add more water if needed.
Squeeze over the lemon juice just before serving. Garnish with fresh parsley.