Wash and core tomatoes and cut them into quarters. For smaller grape tomatoes, cut them in half. Cut onion into quarters. Remove stem from hot pepper and cut in half.
Place tomatoes, onion, hot pepper and garlic cloves in a glass baking dish. Drizzle with olive oil and sprinkle with oregano, salt and pepper and then toss to combine. Spread in a single layer.
Roast 30 minutes, until tomatoes have caramelized.
Transfer to a large stock pot and add chicken stock. Bring to a boil, then reduce temperature and simmer 20 minutes. Adjust seasonings as desired.
Transfer to a food processor or use an immersion blender and puree until smooth. If using processor, you may need to do it in two batches.
Serve and sprinkle with fresh chopped basil and grated Parmesan, if desired.
Notes
Makes 8 servings. Each serving has 6.3 g of carbs and 1.3 g of fiber. Total NET CARBS = 5 g.