Corn Soup with Mushroom Ragout

Name: Corn Soup with Mushroom Ragout
Ingredients: 4 tablespoons olive oil; 1 medium yellow onion, chopped; 1 rib celery, chopped; 1 leek, white part only, chopped; 1 carrot, chopped; 1 clove garlic, chopped; 6 ears corn, shucked and kernels stripped from the cob; 1 bay leaf; pinch saffron threads; 6 cups water; 1 pound assorted fresh mushrooms (such as oyster, shiitake, cremini, trumpet, or portobello), trimmed and sliced about ½” thick; 1 teaspoon fresh thyme, minced; 1 shallot lobe, minced; salt and freshly ground black pepper