Over medium heat, warm olive oil in a large pot or Dutch oven. Add chopped onion, carrots, and celery. Stir often, and cook until the onion is soft and golden.
Add garlic & rosemary (crushed). Cook about one minute until fragrant while stirring constantly.
Puree together stewed tomatoes & fresh tomato. Add to soup pot along with the tomato sauce. Cook together a few more minutes.
Add quinoa, broth, bouillon, red pepper flakes, black pepper, and water. Cover pot and raise heat to high to bring soup to a boil.
Reduce heat to maintain a simmer. Cook soup for 25 minutes.
Meanwhile, cook and crumble Italian sausage (optional) in a preheated pan on medium heat. Drain any grease.
Add spinach to soup pot, and simmer a few minutes more. Add cooked sausage to pot and allow to simmer about five minutes.
Remove pot from heat; then, stir in lemon zest and juice.
Divide into bowls & enjoy!