In the large pot, sauté the onions in the olive oil until they start to glisten, about 3 to 4 minutes. Add the garlic and continue to sauté until it releases its fragrance, about 1 to 2 minutes.
Add the kosher salt, crushed tomatoes, slow roasted tomatoes, roasted peppers, tomato paste, and vegetable broth. Cover and bring up to a slow boil then reduce heat to a simmer. Continue cooking until the tomatoes and peppers are fully heated through, about 20 minutes. Stir in the red wine, if desired. Add more salt and black pepper to taste.
Use the immersion blender to puree the soup in the pot. If you don’t have an immersion blender, you can puree the soup in a regular blender in 2 or 3 batches.
Serve hot with fresh ground black pepper and croutons sprinkled on top.