Dredge the scallops in flour, shaking off the excess.
Bring a large pot of water to a boil.
Place the stock in a large skillet over medium-high heat.
Add the onions, red peppers, and green peppers.
Cook, stirring constantly, and when the onions are translucent, add the mushrooms.
Continue cooking over low to medium heat, stirring occasionally, until the mushrooms have given up their liquid and it has evaporated.
Place the pasta in the boiling water and cook until al dente, about 8 to 9 minutes.
Drain.
While the pasta cooks, add the scallops to the onion mixture in the large skillet and cook, stirring, until the scallops are opaque, about 5 minutes.
Add the tomato sauce, fennel seeds, and 1/2 cup chicken stock to the pan, bring to a boil, then reduce heat and simmer for 1 to 2 minutes.