Maccheroni Soup with Sausage and Porcini

1 ounce dried porcini mushrooms
1/2 medium yellow onion
1 medium carrot
1 celery stalk
3 tablespoons butter
8 ounces mild pork sausage
3/4 pound fresh tomatoes
salt &pepper to taste
6 ounces tubetti or other short tubular pasta

1. Put the dried porcini in a bowl, add 2 cups water, and soak for at least 15 minutes.
2. Peel and finely chop the onion. Peel the carrot and cut into 1/8-inch dice. Peel the back of the celery stalk and cut into 1/8-inch dice.
3. Put the butter in a 5 to 6 quart soup pot over medium high heat. When the butter begins to melt, add the onion, carrot, and celery. Saute until the vegetables begin to brown, about 5 minutes.
4. While the vegetables are sautéing, remove the casing from the sausage and cut into small chunks. Peel the tomatoes and coarsely chop them.
5. When the vegetables are ready, add the sausage. Break up the larger pieces of sausage with a wooden spoon and cook, stirring often, until it loses its raw color. 1 to 2 minutes.
6. Lift the porcini out of the water, squeezing the excess liquid back into the bowl. Do not discard the water. Rinse the porcini under running water, chop them coarsely, and add them to the pot along with the tomatoes, Season lightly with salt and cook, stirring for about 2 minutes.