Mushroom Potato Soup — The Rainy-Sunday Soup

Tulsa is rainy this weekend. The kind of slow, steady September rain that doesn’t storm and doesn’t clear — just hangs at four hundred feet for forty-eight hours, slicking the sidewalks, soaking the lawns of the freshman quad, sending the campus squirrels into hiding. Sunday morning was gray and damp at seven AM and was still gray and damp at noon. The campus was empty. The dorm was unusually quiet because most freshmen had stayed in their rooms reading instead of going to brunch in the rain. I had two hours of reading to do for Monday morning’s American history survey and a soup to make in the second-floor dorm kitchen at one PM.

I made mushroom potato soup because rainy weather wants an earthy, comforting, vegetable-forward soup, and because I’d been wanting to test a technique I’d been thinking about for two weeks since reading a Bittman recipe in the New York Times Cooking section: roasting mushrooms first to develop deep umami before adding them to the soup base. Roasted mushrooms taste fundamentally different from sautéed mushrooms. The dry oven heat at four hundred degrees develops Maillard browning across the cut surfaces of the mushrooms in a way that a sauté pan can’t match without crowding the pan and steaming the mushrooms instead of browning them. The oven is the right tool when you’re cooking mushrooms in volume.

The technique: a pound of cremini mushrooms quartered and tossed with two tablespoons of olive oil, salt, pepper, and a teaspoon of fresh thyme leaves. Spread in a single layer on a parchment-lined sheet pan. Roasted at four hundred for thirty minutes, stirring once at the fifteen-minute mark. The mushrooms come out shrunken to about a third of their original volume, with their cut edges deeply browned and their flavor intensified to almost a steak-like concentration.

While the mushrooms roasted, I built the soup base in a Dutch oven on the stove: olive oil, one diced yellow onion, four cloves of garlic minced, two diced celery stalks, sweated for ten minutes until soft. The roasted mushrooms added back to the pot, including all the dark juices and oil from the sheet pan (every brown bit on that pan is concentrated flavor; you don’t leave any of it behind). Three Yukon Gold potatoes peeled and cubed into half-inch dice. A quart of vegetable broth poured in. Two more sprigs of fresh thyme, a bay leaf, salt, and a generous turn of black pepper. Simmer covered for thirty minutes until the potatoes are tender and the mushrooms have given up another layer of their flavor to the broth.

Now the dual-texture move that I think is the single best technique I’ve discovered for soups in the last six months: pureée half the soup smooth in a blender (in batches if needed; or use an immersion blender on half the pot while leaving the other half untouched), then stir the smooth half back into the chunky half. The result is a soup with a body that pureéed soups don’t have (the chunks of potato and mushroom give it texture and substance) and that chunky soups don’t have either (the pureéed broth gives it the velvety mouthfeel of a cream soup). The smooth half is the broth body. The chunky half is the texture. Together they’re the right consistency for a Sunday-afternoon soup that you eat slowly.

Off the heat, finish with a half-cup of heavy cream stirred in (cream off-heat is the no-break rule that never stops being right) and a splash of dry sherry — about two tablespoons — for the elegant final note. Dry sherry and mushrooms are an old French pairing that traces back to the Burgundian peasant kitchens, and the alcohol burns off in the residual heat while leaving behind the nutty depth that pulls the whole soup together. Adjust salt. Garnish with fresh chopped parsley and a drizzle of olive oil and a few extra fresh thyme leaves on top.

Dustin came up to the second-floor kitchen at four PM Sunday with a paperback of Eudora Welty’s “The Golden Apples” under his arm and his canvas backpack on his shoulder. We ate the soup at the common-room table with a slice of sourdough I’d toasted on the stove rubbed with a halved garlic clove and brushed with olive oil — the cheap version of bruschetta that turns any toasted bread into something restaurant-grade. The rain kept falling against the window. We didn’t leave the dorm. He stayed until ten reading next to me on the common-room couch with the rain on the glass and his own hardcover open on his lap. We didn’t talk much. The kitchen had done all the talking.

Roast the mushrooms first. Half-blend, half-chunky. Cream and sherry off-heat. Here’s the build.

Mushroom Potato Soup

Prep Time: 15 minutes | Cook Time: 30 minutes | Total Time: 45 minutes | Servings: 6

Ingredients

• 2 tablespoons butter
• 1 medium yellow onion, diced
• 3 cloves garlic, minced
• 8 oz cremini or button mushrooms, sliced
• 4 medium russet potatoes, peeled and cubed (about 4 cups)
• 4 cups chicken or vegetable broth
• 1 cup whole milk or heavy cream
• 1 teaspoon dried thyme
• 1/2 teaspoon smoked paprika
• Salt and black pepper to taste
• 2 tablespoons flour (for thickening)
• Fresh parsley or chives for garnish (optional)

Instructions

1. Sauté the aromatics. In a large pot over medium heat, melt the butter. Add the diced onion and cook 4–5 minutes until softened and translucent. Add the garlic and cook 1 minute more.
2. Cook the mushrooms. Add the sliced mushrooms to the pot. Cook 5–6 minutes, stirring occasionally, until they release their liquid and begin to brown at the edges. Season lightly with salt and pepper.
3. Build the base. Sprinkle the flour over the mushroom mixture and stir to coat. Cook 1 minute to remove the raw flour taste, then pour in the broth while stirring to prevent lumps.
4. Add the potatoes. Add the cubed potatoes, thyme, and smoked paprika. Bring to a boil, then reduce heat to a steady simmer. Cook uncovered 18–20 minutes, until the potatoes are completely tender when pierced with a fork.
5. Finish with cream. Reduce heat to low. Stir in the milk or cream and let the soup warm through for 3–4 minutes — do not boil after adding dairy. Taste and adjust salt and pepper as needed.
6. Serve. Ladle into bowls and top with fresh parsley or chives if you have them. Serve with crusty bread and butter.

Nutrition (per serving)

Calories: 210 | Protein: 6g | Fat: 8g | Carbs: 30g | Fiber: 3g | Sodium: 480mg