Air Fryer Mushroom and Thyme Broth
A deeply flavorful mushroom broth made by first air frying mixed mushrooms to concentrate their earthy sweetness, then simmering them with onion, garlic, and thyme. The air frying step removes moisture and intensifies umami, resulting in broth far richer than traditional methods. Vegan, vegetarian, and naturally gluten-free, this broth is elegant enough for French soup bases and wholesome enough for everyday cooking.
- Prep
- 10 min
- Cook
- 59 min
- Total
- 1 hr 9 min
- Makes
- About 5 cups (1.2 liters) strained broth, 4 servings of 1.25 cups each
Steps
Before you start
- Preheat your air fryer to 400°F (200°C) while you clean the mushrooms so it's ready immediately
- Read the timing: most is passive simmering (35–40 min) where you just monitor the pot
- Have a fine-mesh strainer and large heatproof bowl ready before you start cooking
- Optional: save a Parmesan rind from your cheese board—it adds depth during the final simmer
Clean and prep mushrooms
- Wipe mixed mushrooms with a damp paper towel or soft brush to remove dirt.
- Trim the base of stems if visibly soiled.
- Halve smaller mushrooms and quarter larger ones so most pieces are about 2 inches across; leave tiny button mushrooms whole.
- You want relatively even sizes so they cook uniformly in the air fryer.
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Ready when: All mushrooms are cleaned and pieces are roughly uniform in size (about 2 inches)
Tip: Don't rinse mushrooms aggressively—they're porous and absorb water. A damp cloth is faster and preserves their earthy flavor.
Air fry mushrooms to concentrate flavorOven 400°F / 205°C
- Preheat air fryer to 400°F (200°C).
- If your basket fits all mushrooms in one layer without crowding, add them as-is; if needed, lightly spray with olive oil to help browning (optional but recommended).
- Arrange in a single layer.
- Air fry for 12–15 minutes, shaking the basket halfway through.
- The mushrooms will release moisture that mostly evaporates; they should turn deep golden-brown.
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Ready when: Mushrooms are deeply browned; any liquid in basket has mostly evaporated; aroma is rich and concentrated
Tip: If your air fryer is small, work in batches rather than crowding—this gives better browning and faster moisture release.
Cut onion and garlic
- While mushrooms air fry, cut a medium yellow onion into quarters—leave the papery skin on, as it adds color and flavor to the broth without becoming part of the final liquid.
- Smash 3 garlic cloves with the flat side of a chef's knife and leave unpeeled; smashing breaks down the cells to release more flavor.
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Ready when: Onion is in 4 large pieces and garlic cloves are flattened
Combine all ingredients and heat
- Transfer the roasted mushrooms to a large 6–8 quart pot.
- Add the onion quarters, smashed garlic, 5 thyme sprigs, 2 bay leaves, and 6 cups cold water.
- Place pot over medium-high heat and bring to a boil, stirring occasionally (about 6–7 minutes).
- You'll see large, rolling bubbles breaking the surface.
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Ready when: Large, rolling bubbles break the surface continuously
Tip: Use cold water so the mushrooms release flavor slowly and evenly; hot water can shock them and leach flavor too quickly.
Simmer to extract mushroom flavor
- Once boiling, reduce heat to medium-low and maintain a gentle simmer where small bubbles rise steadily but the pot doesn't roll vigorously.
- Do not cover the pot—you want some evaporation to concentrate flavors.
- Simmer for 35–40 minutes.
- The broth will deepen in color to a rich golden-brown, and the mushrooms will look pale and exhausted.
- The aroma will become deeply savory and umami-rich.
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Ready when: Broth is golden-brown and fragrant; mushrooms look pale and cooked out
Tip: Avoid a rolling boil—it can make broth cloudy and cause flavor to evaporate too fast. A gentle simmer extracts cleaner, clearer broth.
Taste and season
- Remove pot from heat and let broth cool for 1–2 minutes so it's safe to taste.
- Taste carefully.
- Add salt starting with about 0.5–1 teaspoon per 2 cups of broth, then a pinch of black pepper.
- Stir and taste again.
- Adjust seasoning to your preference—mushroom broth should taste rich and savory, not salty.
- If using the optional Parmesan rind, add it now and stir; it will soften and add umami depth.
- Simmer gently on medium-low heat for 2 more minutes to let flavors meld.
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Ready when: Broth tastes well-seasoned and balanced; flavors are melded
Tip: Taste gradually—you can always add more salt, but you can't remove it. Mushroom broth is savory enough that you might need less salt than you expect.
Strain out solids
- Set a fine-mesh strainer or sieve over a large heatproof bowl.
- Carefully pour the hot broth through the strainer, allowing solids (mushrooms, onion, herbs, garlic) to collect in the strainer.
- Gently press the solids against the strainer with the back of a spoon to extract any remaining liquid—press gently, don't crush, or you'll cloud the broth.
- Discard all solids.
- Let the broth cool for 5–10 minutes before using or storing.
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Ready when: Clear, golden-brown liquid has been separated from solids; strainer holds only spent mushrooms and aromatics
Tip: If you press too hard, fine particles can cloud your broth. A gentle hand makes a clearer, more elegant broth—though slight cloudiness is harmless.
Good to know
Tips
- This broth freezes beautifully in ice cube trays—pop out cubes to add umami depth to soups, grains, risotto, or sauces without needing to thaw a whole container.
- If your broth tastes flat despite seasoning, you may need more mushrooms next time. A ratio of 1.25 lbs mushrooms to 6 cups water is a baseline; some cooks prefer 1.5 lbs for richer, more concentrated broth.
- No air fryer? Roast mushrooms in a 425°F (220°C) oven on a rimmed baking sheet for 20–25 minutes, shaking the pan halfway through. The result is slightly less intense but still excellent.
- Save the spent mushroom solids after straining to add to compost or to a freezer bag for later use in vegetable broth—they've given up their flavor but still have structure and minerals.
Make ahead
Prepare the broth up to 2 days ahead. Cool completely, pour into an airtight container, and refrigerate. Reheat gently on the stovetop over medium heat until steaming. Alternatively, freeze the broth in ice cube trays for easy portioning, then transfer cubes to a freezer bag for up to 3 months.
Storage & reheating
Room temperature (covered): up to 2 hours. Refrigerator (airtight container): up to 5 days. Freezer (in ice cube trays or containers): up to 3 months. To reheat: Gently warm on the stovetop over medium heat, stirring occasionally, until steaming.
Substitutions
- mixed fresh mushrooms (cremini, button, shiitake, oyster) → All cremini mushrooms, all button mushrooms, or mixed with dried porcini. A single type yields a more straightforward flavor; adding dried porcini (rehydrate first or add directly) deepens umami significantly.
- fresh thyme sprigs → 3 sprigs fresh oregano or 1 tablespoon dried thyme. Fresh is more aromatic; dried thyme works equally well and needs no fishing out of the strainer.
- bay leaves → 2 sprigs fresh sage or 1 teaspoon dried sage. Sage adds an herbaceous note that complements mushroom flavor. Different from bay but equally delicious.
- cold water → Half water and half dry white wine or vegetable stock. Wine adds acidity and complexity; stock adds depth, though it may dilute the mushroom flavor depending on stock intensity.
