Celeriac Soup with Hazelnut Crumble

There's something quietly magical about celeriac that most people overlook entirely. I discovered it by accident one autumn when a farmer at the market practically thrust a knobby root into my hands, insisting I had to try it roasted. That first spoonful of silky soup, warm and earthy with that unexpected hazelnut crunch on top, felt like finding a secret ingredient I didn't know I'd been searching for. Now it's become my go-to comfort when the weather turns cool and I need something that feels both sophisticated and deeply, genuinely nourishing.

I made this for my sister on a rainy Sunday when she arrived unannounced, claiming she was tired of the same old soup rotation. Watching her face when she tasted it, then immediately asking for the recipe mid-spoonful, felt like winning something. She now texts me photos of her attempts, and there's genuine pride in knowing I handed her something she genuinely wanted to recreate.

Ingredients

• Celeriac: Don't let the alien appearance fool you; this knobby root becomes pure velvet when roasted and blended, with a flavor that's nutty and subtle rather than strongly celery-like.
• Potato: Added for body and creaminess without relying solely on dairy, it practically dissolves into the soup.
• Vegetable broth: Quality matters here since it's the backbone of everything; homemade is ideal but a good store-bought brand won't let you down.
• Hazelnuts: Toast these yourself rather than using pre-roasted; the difference in flavor depth is honestly remarkable and worth the three extra minutes.
• Olive oil: Use your better oil for the final drizzle if you have one, though the good stuff shines when it's not heated.
• Heavy cream or plant-based alternative: Optional but transforms the soup from good to genuinely luxurious; if skipping, add an extra splash of broth.

Instructions

Prepare and roast the celeriac:

Preheat your oven to 200°C and toss those peeled, cubed celeriac pieces with olive oil, salt, and pepper until they're evenly coated. Spread them on a tray in a single layer and roast for 25 to 30 minutes, giving them a gentle stir halfway through, until they're soft enough to break apart easily and golden at the edges.

Build the soup base:

While the celeriac caramelizes, warm olive oil in a large pot and let the chopped onion soften for about 4 minutes until it turns translucent and fragrant. Stir in your minced garlic and diced potato, letting them cook together for another couple of minutes until the kitchen smells irresistible.

Simmer everything together:

Add the roasted celeriac to the pot along with your vegetable broth, bringing it to a gentle boil before reducing to a simmer for 15 to 20 minutes. You're waiting for the vegetables to become so tender they practically fall apart when you look at them.

Toast the hazelnut crumble:

In a separate skillet over medium heat, toast your roughly chopped hazelnuts for about 3 to 4 minutes, stirring frequently, until they release their deep, toasty aroma and begin to darken slightly. Add butter and sea salt, letting everything coat together until glossy, then set aside to cool.

Blend into silky smoothness:

Use an immersion blender to purée the soup directly in the pot, moving it around until you've achieved that luxurious, velvety consistency. If using a countertop blender, work in careful batches and return everything to the pot, then stir in your cream if you're using it.

Season and serve:

Taste your soup and adjust the salt and white pepper to your preference, knowing that the hazelnut topping will add another layer of seasoning. Ladle into bowls and top generously with that golden crumble and fresh parsley if you have it.

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This soup became my winter remedy for the 3 p.m. slump when the afternoon light starts fading too early. There's something about spooning through that velvety warmth while the hazelnut crumble releases its flavor that makes time slow down just enough.

Variations to Explore

Once you've mastered the basic version, the variations practically suggest themselves. Add a pinch of fresh thyme during the simmer for earthiness, or squeeze in lemon juice at the end for brightness that cuts through the richness beautifully. Some nights I stir in a whisper of truffle oil right before serving, which feels indulgent but takes maybe five seconds.

Making It Your Own

The beauty of this soup is how forgiving it is once you understand the core technique. I've added crispy sage leaves, smoked paprika, a touch of curry powder, and even swapped the hazelnuts for toasted walnuts or almonds depending on what was in the pantry. The structure stays solid while you're free to improvise.

Storage and Make-Ahead

This soup actually improves after a day or two as the flavors marry and deepen, making it perfect for meal prep without any of the effort. Store it in airtight containers in the refrigerator for up to four days, or freeze for up to three months, thawing overnight before reheating gently. The hazelnut crumble stays best if you make it fresh each time, but you can toast the nuts ahead and finish them with butter just before serving.

• Reheat gently on the stovetop rather than in the microwave to maintain that silky texture.
• Make the hazelnut crumble fresh each serving for maximum crunch, or prepare the toasted nuts ahead and finish with butter when ready to eat.
• If your soup thickens too much after refrigeration, whisk in warm broth a little at a time until it reaches your preferred consistency.

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This soup has become my answer to almost every season and occasion, the kind of dish that reminds me why I love cooking in the first place. Make it once, and you'll understand why.

Recipe FAQ

→ What does celeriac taste like?

Celeriac offers a mild, earthy flavor reminiscent of celery and parsley with subtle sweetness. Roasting intensifies its natural sugars while mellowing any bitterness.

→ Can I make this soup ahead?

Absolutely. The base keeps refrigerated for 4-5 days and freezes beautifully for up to 3 months. Add the hazelnut crumble fresh when serving for optimal texture.

→ How do I get the silkiest texture?

Roasting the celeriac first creates smoother results than boiling alone. Use an immersion blender for 2-3 minutes or pass through a fine-mesh sieve for restaurant-quality silkiness.

→ What can I substitute for hazelnuts?

Toasted pecans, walnuts, or even pumpkin seeds work beautifully. Each brings slightly different flavor notes while maintaining that essential crunch contrast.

→ Is this suitable for special diets?

Simply swap cream for coconut milk or oat milk and use plant-based margarine instead of butter. Naturally gluten-free and packed with fiber from the celeriac.

→ How do I store leftovers?

Cool completely and refrigerate in airtight containers. Reheat gently over low heat, adding a splash of broth or water if needed. Store crumble separately at room temperature.