How to best hold wild rice I'm making mushroom soup recipe and I'm looking forward to serving it at dinner tomorrow. I have powdered the shitakes, sliced the mushrooms and the wild rice is in the oven now. In order to serve the best possible soup, where should I stop preparation tonight? If I were comfortable with all of the ingredients, I would prepare the soup up to the addition of cream. Unfortunately, I know nothing of wild rice, and how best to hold it. Will it be OK overnight in the fridge? Even better, can I leave the soup (up to the cream addition) on the porch overnight? It's expected to dip 10 degrees F below freezing and stay there until morning.

EDIT: My best guess is to add the rice to the soup now, store overnight on the porch, and add the cornstarch slurry, cream and the rest just prior to service. Would the wild rice hold up to that?
Wild rice, if left in the soup, will absorb water until it is bloated and mushy.   You should therefore refrigerate it separately, and add it as you are finishing the soup.

Foxes, deer, raccoons and so on aside, assuming the temperature outside is at 40 F / 4 C or lower steadily, you can use it as a giant fridge/freezer.  Of course, if the temperate goes as low as you have indicated, your soup base is likely to freeze, which may be inconvenient.