Adam Liaw’s game-changing secret to making an even better pumpkin soup
Master this classic, warming soup and experiment with different ways to put your own stamp on it.
The classic pumpkin soup is the perfect balance of natural sweetness from pumpkin and savoury stock, and it can be taken in many different directions. Here’s how to make the best pumpkin soup.
Ingredients
½ butternut or ¼ Kent pumpkin (about 1 kg)
2 tbsp olive oil, or 50g butter, plus extra for the sourdough
1 brown onion, diced
1 carrot, diced
1 celery stick, diced
1 potato, peeled and diced
1 litre vegetable stock, or chicken stock
1 tsp vegetable stock powder
150ml thickened cream, plus extra to serve
salt and black pepper, to season
a few thick slices of sourdough, grilled to serve
Method
Step 1
Heat the oven to 160C fan-forced (180C conventional) and place the pumpkin, skin and all, in a baking dish. Roast, uncovered, for 90 minutes. You don’t need to season it or cover it with oil. Allow the pumpkin to cool, then scoop out the seeds and discard them. Scoop the flesh from the skin and discard the skin.
Step 2
Heat a large saucepan over medium heat and add the oil or butter. Then add the onion, carrot and celery and fry for about 6 minutes, until softened. Add the potato and fry for a further 2 minutes. Season well with salt. If you are adding spices (see below), stir them in now.
Step 3
Add the stock and bring to a simmer. Simmer for 20 minutes, then stir the scooped pumpkin flesh into the liquid. Remove from the heat and blend to a very smooth puree in a high-speed blender. If you prefer a chunkier soup, you can use a stick blender. After blending, return the soup to the saucepan, warm through, then stir in the cream. Taste again and adjust the seasoning.
Step 4
Drizzle the bread generously with olive oil and grill it on a grill pan until golden brown. Swirl a little extra cream into the soup and grind over a little black pepper, if you like. Serve the soup with the grilled bread.
Masterclass
Roast the pumpkin
If there’s one thing that you can do to improve your pumpkin soup, it’s roasting. There are three main reasons why this is the game-changer.
Firstly, roasting significantly intensifies the flavour of the pumpkin by reducing the amount of water it contains. One kilogram of raw pumpkin will yield about 500 grams of roasted pumpkin flesh after cooking. Aside from leaving behind the seeds and skin, a lot of water is removed in the cooking. This is also why I don’t oil the pumpkin before roasting – you want to dry it out a bit.
Secondly, roasting rather than boiling develops more complex flavours. Higher temperatures break down longer-chain starches in the pumpkin to produce sweeter compounds over time. Maillard reactions (sugar-protein reactions) and caramelisation (sugar oxidisation reactions) occur more quickly at higher temperatures.
Boiling simply can’t achieve this. Water boils at around 100C, which is too low for significant caramelisation to occur. Caramelisation starts to kick in around 105C for fructose and up to 170C for sucrose.
By baking at 160C fan-forced, you hit that sweet spot. It’s hot enough to encourage those complex Maillard reactions and some caramelisation without burning or blackening the pumpkin, giving you a far more flavourful result.
In all, this means your long-roasted pumpkin will taste more intense, complex and sweeter than pumpkin that is boiled for 20 minutes. And when the key ingredient in your soup is pumpkin, the better you make it taste, the better your soup will be.
The final benefit of roasting pumpkin has nothing to do with taste. It’s just easier. Pumpkin can be difficult to cut if your knife isn’t sharp or heavy enough, so roasting half a pumpkin as it is makes easy work of it. Once cooked, you can scoop out the parts you want with a spoon.
Sweetness v umami
The balance of sweetness and umami is a powerful one in food. It’s what makes oyster sauce a perfect stir-fry seasoning, or Worcestershire sauce a great addition to stews, and it’s why the great Tetsuya Wakuda once told me that when you add soy sauce to a dish (umami), its taste should be balanced with a pinch of sugar (sweetness).
In pumpkin soup, the sweetness comes naturally from the roasted pumpkin, and we balance that with umami-tasting stock. All stocks are umami-tasting liquids, which is why they make great ingredients in savoury cooking.
Cook a pumpkin in water and you can turn it into desserts such as pumpkin pie or pudding, but if you dial up the umami, that’s what makes a great pumpkin soup.
Some people like to add umami ingredients such as miso or soy sauce, but I prefer to keep it simple by using a good stock, then fortifying it with a spoonful of stock powder.
Blending hot liquids
Perhaps it’s controversial, but for me, pumpkin soup has to be velvety smooth.
Blending hot liquids can be tricky. When you blend hot liquids, you’re essentially creating a lot more surface area, which leads to rapid steam release. In a sealed blender, this steam builds up pressure, and that’s when things can get a bit dicey.
The good news is, there’s a simple fix. Remove the stopper from the lid of your blender and cover the opening with a tea towel. This allows the steam to escape safely. Make sure you start blending on a low speed and gradually increase it. This prevents a sudden surge of steam and manages the pressure.
Alternatively, you can use a stick blender, but it can be difficult to get a silky consistency.
Importantly, blending will change the taste profile of the soup. The process releases additional sweetness from the chunks of pumpkin into the soup, so make sure you taste and season the soup again after blending.
Variations
I have kept this pumpkin soup recipe very classic, but there are endless opportunities to put your own spin on it. Here are a few ideas to try:
- Spice the soup with 2 teaspoons of your favourite curry powder added when frying the onion, carrot and celery.
- Add ginger along with this mirepoix.
- Add red curry paste or miso.
- Replace the cream with coconut cream.
- Roast the pumpkin with rosemary.
- Crumble blue cheese over the top.
- Spread your grilled bread with pesto or soft goat’s curd.
- Serve it with croutons mixed with roasted almonds, or with mushrooms on toast.
All of these are excellent variations that will ensure that your classic pumpkin soup never gets boring.
The best recipes from Australia's leading chefs straight to your inbox.
Sign upMore:
Adam Liaw is a cookbook author and food writer, co-host of Good Food Kitchen and former MasterChef winner.
