How to Make It
In a large enameled cast-iron casserole, heat the olive oil. Add half of the sausages and cook over moderate heat, turning, until browned all over, 5 minutes. Transfer to a plate; repeat with the remaining sausages.
Add the fennel wedges to the casserole and cook over moderate heat, stirring, until golden, about 5 minutes. Add the onion, garlic, fennel seeds and 1 teaspoon of salt and cook, stirring, until the fennel is lightly browned, about 3 minutes. Add the tomatoes and their juices, the wine and chiles. Tuck the sausages into the sauce. Cover and cook over low heat for 15 minutes. Uncover and simmer until the sausages are cooked through and the sauce is thickened, about 45 minutes longer. Garnish the stew with fennel fronds and serve over polenta.
Small, spicy dried red Mexican pequin chiles are available at Latin American markets and specialty food stores.