Prep your onion, carrots, and celery. I just roughly chopped the carrots and celery.: The kitchen greets you with the bright, vegetal scent of chopped onion , carrots , and celery , and that freshness is crucial because these aromatics form the soup’s base. Use a sharp knife so the pieces are uniform, which helps them soften at the same rate and avoids inconsistent bites. You should hear a crisp chop and see the colors pop against the cutting board. A common mistake is rushing the knife work and ending up with uneven sizes, which leads to some pieces being undercooked while others are mushy.
Add the oil and butter to a large soup pot over medium-high heat. Add the onion, carrots, and celery. Sauté for 7 minutes, stirring occasionally.: Early on the pan should shimmer with olive oil and foam from the butter , releasing a nutty scent as it warms. As the vegetables hit the pot you will hear a soft sizzle and see the edges of the onion turn translucent, the carrots begin to soften, and the celery wilt. Stir every couple of minutes to prevent sticking and to promote even browning, which deepens flavor through the Maillard reaction. If your heat is too high, the vegetables will brown too fast and taste bitter, so lower it if you notice rapid darkening.
Stir in the garlic, Italian seasoning, and flour. Cook for 1-2 minutes.: When you add minced garlic and dried herbs, an immediate fragrant lift should sweep through the kitchen, but this phase is brief to avoid burning the garlic . Sprinkle the flour and stir constantly so it coats the vegetables, forming a light roux that will thicken the broth. The mixture will feel slightly pasty on the spoon which is exactly what you want, and cooking for a minute releases the raw flour flavor. Watch carefully because too long here will darken the roux and change the taste profile undesirably.
Whisk in the chicken broth until the flour is dissolved.: As you pour in the chicken broth , whisk briskly so there are no lumps and the roux integrates into a smooth liquid. The aroma will shift from toasty notes to a fuller, soup like scent as the broth heats. You should see the mixture become glossy and slightly thickened. A common pitfall is adding the liquid too quickly which can create clumps, so whisk steadily and scrape the pot bottom to lift any caramelized bits for maximum flavor.
Stir in the rice.: Once the broth is smooth, add the uncooked wild rice , which will begin to hydrate and swell. The grains will sink initially and later float as they absorb liquid, and you will notice the broth becoming subtly clouded. Give it a stir to ensure the rice is evenly distributed so it cooks uniformly. A mistake to avoid is adding too little liquid, which can cause the rice to cook unevenly and stick to the pot.
Increase the heat to high and bring the soup to a boil. Once it's just boiling, cover the pot with the lid slightly ajar. Reduce the heat so it's gently boiling for 15 minutes.: Bring the pot up to a rolling boil where you will see steady bubbles across the surface and feel heat radiating. Then lower the flame until bubbles are gentle and rhythmic, a simmer that encourages gradual hydration of the wild rice . Covering with the lid slightly ajar traps steam but prevents overpressure, which keeps the texture tender. If you leave it fully covered, the liquid may boil too vigorously and reduce too quickly, leading to undercooked rice or a too thick soup.
If you haven't already prepped the turkey and mushrooms, you can do it now.: This is the moment to slice the cremini mushrooms and shred or cut up the cooked turkey . The mushrooms should be clean and sliced to a consistent thickness so they cook evenly, and the turkey should be in bite sized pieces for balanced distribution. You should notice a dry, earthy mushroom scent when sliced, and the turkey will give a savory reminder of the original roast. Avoid cutting pieces too large, which can make the soup awkward to eat.
Add the turkey and mushrooms to the soup. Increase the heat again so it just comes to a boil, then reduce the heat so it's simmering again and continue cooking the soup for another 15-20 minutes (cover with lid slightly ajar) or until the rice is tender (wild rice does have a bit of "chew" to it, though).: When you drop in the turkey and mushrooms , the pot will release a richer aroma as the ingredients mingle. Bringing it briefly to a boil helps ensure the turkey heats through, and the simmer that follows coax the wild rice to reach its ideal chew, which is tender with a bit of resistance. Stir occasionally to prevent sticking and to check rice doneness. A frequent error is overcooking the turkey , which dries the meat, so watch the timing and remove from heat when the rice is done.
Stir in the cream (if using). Season soup with salt & pepper as needed.: Adding the heavy/whipping cream at the end imparts a silky finish and softens the flavors, transforming the broth into something more luxurious. Warm the cream gently into the soup and notice how it mellows acidity and ties ingredients together. Taste and finish with salt and pepper , adding in small increments to avoid over seasoning. If you oversalt, dilute with a bit more broth or a peeled potato to absorb excess salt, which is a salvage technique to keep in mind.