In a soup pot, heat oil, two turns of the pan, over medium-high. Add the onion, celery, peppers and garlic; season with salt and pepper. Cook, stirring occasionally, until softened, 7-8 minutes.
Stir in the stock, tomatoes and the parmesan rind, if using. Bring to a boil. Add the green beans and pasta; cook at a low rolling boil until the noodles are al dente and the beans are crisp-tender, about 5 minutes.