Why This Recipe Works

Hands-off method: The slow cooker does the heavy lifting while you march, read, or volunteer.
Whole-grain goodness: Wild rice keeps its chewy integrity, so the soup never turns to wallpaper paste.
Umami triple-threat: Dried porcini soaking liquid, soy sauce, and miso build layers of savoriness without meat.
Creamy-no-cream: A single can of white beans puréed with a splash of broth gives silky body that’s dairy-free.
Make-ahead hero: Flavors bloom overnight; reheat on the stovetop while you watch the parade.
Feeds a crowd: Doubles beautifully for church suppers or community center potlucks.

Ingredients You'll Need

Wild rice is the star here—technically an aquatic grass seed, not rice at all—harvested by hand in Minnesota and Wisconsin lakes. Look for glossy, charcoal-black grains; avoid packages labeled “broken” unless you want a thicker porridge. Cremini (baby bellas) give a deeper flavor than white mushrooms, but feel free to mix in shiitake caps or even a handful of reconstituted dried porcini for extra forest-floor intensity. The dried porcini soaking liquid is liquid gold—don’t toss it! A tablespoon of white miso may seem odd, but it melts into the broth and quietly amplifies everything. If you’re gluten-free, swap tamari for soy sauce and be sure your miso is certified GF. Cannellini beans blended with a cup of the hot broth create that luxurious mouthfeel without heavy cream; navy or great northern work just as well. Finally, a small splash of dry sherry added at the end brightens the earthy flavors—if you’re avoiding alcohol, substitute 1 tablespoon apple-cider vinegar.

How to Make Slow Cooker Mushroom and Wild Rice Soup for MLK Day

1 Rinse and toast: Place 1 cup wild rice in a fine-mesh sieve and rinse under cold water until the water runs clear; this removes excess starch and any lake-bottom sediment. While it drains, heat 1 tablespoon olive oil in a skillet over medium heat. Add the rinsed rice and toast for 2 minutes, stirring, until the grains smell nutty. Transfer to the slow cooker insert—this tiny step prevents the rice from clumping.

2 Sauté aromatics: In the same skillet, melt 2 tablespoons butter with 1 tablespoon olive oil. Add 1 diced large yellow onion, 2 chopped carrots, and 2 chopped celery stalks. Cook 5 minutes until edges caramelize. Stir in 3 minced garlic cloves, 1 teaspoon dried thyme, ½ teaspoon dried rosemary, and ¼ teaspoon freshly ground black pepper; cook 30 seconds. Scrape every browned bit into the slow cooker—flavor tax.

3 Prep mushrooms: Wipe clean 1 pound cremini mushrooms with a damp paper towel; never soak them—they’ll sponge up water like, well, mushrooms. Slice ½-inch thick. Sauté half the batch in the skillet for 4 minutes until they shrink and tan; this concentrates flavor. Add both the sautéed and raw mushrooms to the cooker for textural contrast.

4 Deglaze and bloom: Pour ½ cup low-sodium vegetable broth into the hot skillet and scrape the fond with a wooden spoon. Whisk in 1 tablespoon soy sauce, 1 tablespoon white miso, and ½ ounce dried porcini mushrooms that have soaked 20 minutes in 1 cup hot water. Pour the whole umami slurry over the rice mixture.

5 Add liquid: Stir in 4 cups additional vegetable broth and 1 bay leaf. The liquid should just cover the ingredients by ½ inch; if not, add water. Cover and cook on LOW 6–7 hours or HIGH 3½–4 hours, until wild rice kernels split open like tiny butterflies.

6 Creamy base: When rice is tender, remove bay leaf. Drain and rinse 1 (15-oz) can cannellini beans. Transfer beans and 1 cup hot soup broth to a blender; purée until silky. Stir back into the slow cooker for body without dairy.

7 Finish and brighten: Taste; add salt and plenty of freshly ground black pepper. Stir in 2 tablespoons dry sherry and 1 cup frozen peas (they thaw instantly). Let stand 5 minutes. Ladle into warm bowls, drizzle with extra-virgin olive oil, and shower with chopped parsley.

Expert Tips

Overnight Soak

If you remember, soak wild rice in boiling water 30 minutes before cooking; it shortens the slow-cook time by an hour and encourages more even splitting.

Control Salt

Hold off salting until the end; broth reductions and miso vary wildly in sodium. Taste after the beans are blended, then adjust.

Freezer Portion

Freeze single servings in silicone muffin cups; pop out frozen pucks and store in zip bags for up to 3 months. Reheat with a splash of broth.

Sherry Swap

No sherry? Use 1 tablespoon apple-cider vinegar plus 1 teaspoon maple syrup for a similar sweet-tart lift.

Variations to Try

Storage Tips

Cool leftovers to room temperature within 2 hours; wild rice can sour if left warm too long. Refrigerate in airtight containers up to 5 days. The soup will thicken as the rice keeps drinking liquid—thin with broth or water when reheating. For longer storage, ladle into quart-size freezer bags, lay flat to freeze (saves space), and keep up to 3 months. Thaw overnight in the fridge or break straight into a saucepan with a splash of water over low heat. If feeding a crowd the next day, hold the peas and sherry until the reheat; their color and aroma stay brighter.

Frequently Asked Questions

Brown rice cooks faster and will disintegrate into mush. If you must, add it during the last 1½ hours on LOW, but expect a softer texture.

Remove lid, switch to HIGH, and simmer 30 minutes with the beans blended in; evaporation will tighten it up. Alternatively, whisk 1 tablespoon cornstarch with cold broth and stir in.

Yes, if you use certified-GF tamari and miso. Wild rice is naturally gluten-free.

Yes, 3½–4 hours on HIGH works, but the flavors won’t meld as deeply. If schedule allows, LOW is worth the wait.

A crusty slice of honey-oatmeal or skillet cornbread complements the nutty rice. For a celebratory touch, serve with jalapeño-cheddar cornbread.