Warm up a chilly evening with this hearty dish.
Heat the oil in a saucepan over medium heat. Cook sausage, stirring until it breaks into small pieces and is no longer pink, about 10 minutes. Remove sausage with a slotted spoon, and set aside.
Pour off all but 2 tablespoons of the rendered fat, and discard. Raise heat to medium high, and add the onions; cook, stirring, until golden, about 8 minutes. Add tomatoes, stock, and herbs; simmer over medium heat until the liquid starts to thicken, about 20 minutes. Add the sausage, squash, carrots, parsnips, and fennel; cover, and simmer until the vegetables are tender, about 10 minutes. Add brussels sprouts; cook, covered, about 5 minutes more. Uncover; cook, stirring occasionally, until liquid thickens, 10 to 15 minutes more. Season with salt and pepper; serve hot.
To make peeling the onions easier, soak in warm water for 30 minutes to wrinkle the skins.