Heat a large pot over medium-high heat. Add the sausage and cook, breaking it up with a wooden spoon, until browned and cooked through, about 7 minutes. Add the chopped tomatoes, noodles and stock and bring to a boil. Reduce to a simmer, cover and cook, stirring occasionally, until the noodles are tender, 25 to 30 minutes. Stir in the peas (if they're frozen, they'll thaw pretty much immediately when stirred in). Season with salt and pepper. Top with cheese and herbs, if desired.