Heat olive oil in a large pot over medium heat. Add onion, garlic, carrots, celery, and bell pepper. Sauté for 5 minutes until the vegetables begin to soften.
Add zucchini, diced tomatoes, vegetable broth, cannellini beans, chickpeas, red lentils, Italian seasoning, paprika, salt, and black pepper. Stir well to combine.
Bring the soup to a boil, then reduce heat and simmer for 25-30 minutes until the lentils are tender and the vegetables are cooked.
Stir in fresh spinach during the last few minutes of cooking until wilted.
Add a squeeze of lemon juice and garnish with parsley or Parmesan cheese before serving.
