Heat oil in a large pot. Add the vermicelli and stir-fry over high heat u ntil well-coated and starting to turn golden, about 1 minute. Add onion and garlic and continue stirring until the onion wilts slightly, about 1 minute. Add the tomatoes, chiles, oregano, salt & pepper, and simmer until the tomatoes wilt, about 3 minutes. Stir in the vegetable broth and bring to a boil. Reduce heat and simmer u ntil most of the liquid is absorbed, about 15 minutes (add more stock, if neces sary, during cooking). Transfer to a serving dish, and sprinkle with Parmesan cheese, if desired. Serve immediately.