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Light roasted leek and potato soup is made by roasting leeks, potatoes and garlic at 200 C / 400 F for 35 minutes, then simmering them in stock and blending until smooth. There’s no cream and no butter. Two tablespoons of olive oil cover the whole pot.
I’ll be honest, I used to boil everything and wonder why leek and potato soup tasted flat. Roasting fixed that. The leeks turn sweet. The potatoes go golden at the edges. The garlic gets soft and mellow.
One thing to watch. Leek edges go from deep brown to black fast, and black leeks taste bitter. Stir the pan at the 20-minute mark and pull out anything that’s darkening.
The pot makes four bowls at about 270 calories each. It sits right in your weekday rotation because it keeps for days.
Why You’ll Love This Recipe
- Roasting gives sweetness without any cream or butter
- Only 2 tbsp olive oil for the whole pot
- Keeps 4 to 5 days and freezes well
- Costs about $2 a bowl with basic ingredients
Ingredient Notes
- Leeks: Use the white and light green parts only. The dark green tops are tough and fibrous, so save them for stock.
- Yukon Gold potatoes: Their medium starch gives a smooth, creamy-feeling soup. Russets work but blend thicker and turn gluey more easily.
- Low-sodium vegetable stock: Low-sodium lets you control the salt. Chicken stock works too, though the soup is no longer vegan.
- Lemon juice: A tablespoon stirred in after blending brightens the sweet roasted flavor. White wine vinegar is a fair swap at 1 tsp.
Light Roasted Leek and Potato Soup with Garlic and Thyme
Ingredients
Method
- Heat the oven to 200 C / 400 F. Halve the leeks lengthwise, slice them into 1 cm half-moons, and swish them in a bowl of cold water to loosen the grit. Lift them out with your hands, pat dry, and peel and chop the potatoes into 2.5 cm chunks.
- Tip the leeks, potatoes, whole unpeeled garlic cloves and thyme sprigs onto a 33 x 46 cm / 13 x 18 inch sheet pan. Add the olive oil, 1/2 tsp of the salt and the pepper, toss well, and spread everything in a single layer.
- Roast for 35 minutes, stirring once at the 20-minute mark, until a fork slides easily into the potatoes and the leeks have golden-brown edges. Dark brown tips are fine. Pull out and discard any pieces that have gone black, since they taste bitter.
- Squeeze the soft garlic out of its skins into a 4-quart / 3.8 L soup pot and discard the skins and thyme stems. Add the roasted vegetables and the stock, using a splash of it to scrape the browned bits off the pan. Bring to a simmer over medium heat and cook for 10 minutes.
- Blend until smooth, 1 to 2 minutes with an immersion blender. With a countertop blender, work in batches and fill it no more than halfway, with the lid vented. Stir in the lemon juice and the remaining 1/2 tsp salt, thin with a splash of water if it’s too thick, and taste. Serve hot, topped with chives.
Notes
- Wash the leeks after slicing. Grit hides between the layers.
- Roast in a single layer on the 33 x 46 cm pan.
- Pull out any blackened leek pieces before simmering.
- Add the lemon juice and the second half of the salt after blending.
- The soup thickens in the fridge. Loosen it with a splash of stock.
Tips for Success
- Slice the leeks first, then swish them in a bowl of cold water and lift them out so the grit stays behind.
- Cut the potatoes into 2.5 cm chunks so they finish roasting at the same time as the leeks.
- Spread the vegetables in a single layer on the 33 x 46 cm pan so the edges brown instead of steam.
- Use an immersion blender, or pulse a countertop blender only until smooth, since long high-speed blending makes potato soup gluey.
- Add the lemon juice and the last half teaspoon of salt after blending, then taste, because flavor shifts once everything is pureed.
Variations
- Stir in 120 ml whole milk or oat milk at the end for a creamier bowl, and warm it through gently.
- Blend in one drained 400 g can of white beans for extra protein and a thicker body.
- Finish with crisped bacon bits or toasted pumpkin seeds for crunch and a salty edge.
Storage and Reheating
Roasted leek and potato soup keeps in an airtight container in the fridge for 4 to 5 days. Get it into the fridge within 2 hours of cooking.
It also freezes for up to 3 months. Leave 2 cm of space at the top of the container because the soup expands, and thaw it overnight in the fridge.
Reheat on the stove over medium-low heat for 8 to 10 minutes, stirring often, until steaming hot. The soup thickens as it sits, so stir in 2 to 4 tbsp of water or stock. In the microwave, use 90-second bursts at 70% power and stir between each one.
Serving Suggestions
Ladle the soup into wide bowls while it’s hot. Finish with a drizzle of olive oil, snipped chives and a few cracks of black pepper.
Grilled cheese on sourdough turns a bowl into dinner. A slice of toasted rye with hummus works too, and so does a green salad with a lemon dressing for a lighter lunch.
Kids tend to eat it when it’s blended extra smooth. Leftovers travel well in a thermos for school or work lunches.
FAQ
Why is my leek and potato soup gluey?
Gluey soup comes from overworked potato starch, usually after long blending in a high-speed blender. Blend only until smooth, about 1 to 2 minutes with an immersion blender. Yukon Gold potatoes hold up better than russets. If it’s already gluey, stir in 60 to 120 ml hot stock gently by hand.
Can I use russet potatoes instead of Yukon Gold in roasted leek and potato soup?
Yes, russets work. They roast up drier and fluffier, so the soup comes out a little thicker and turns gluey more easily if you over-blend. Use the same 600 g, peeled and cut into 2.5 cm chunks, and keep an extra 60 ml of stock nearby to loosen it.
Can I freeze light roasted leek and potato soup?
Yes, it freezes for up to 3 months and stays smooth, since this version has no cream or milk to split. Cool it fully, leave 2 cm of headspace in the container, and thaw overnight in the fridge. Reheat on the stove and whisk to bring back the smooth texture.
How do I know when the leeks and potatoes are done roasting?
The potatoes are done when a fork slides in with no resistance, usually around the 35-minute mark at 200 C / 400 F. The leeks should have golden-brown edges with a few dark brown tips. If any pieces are black, pick them out before simmering, because burnt leek tastes bitter and will carry through the whole pot.
What goes with roasted leek and potato soup to make it a full dinner?
Grilled cheese on sourdough is the easy answer, and a crusty baguette or toasted rye works too. A bowl alone is about 270 calories, so bread or a sandwich turns it into dinner. For a lighter lunch, serve it with a green salad dressed with lemon juice and olive oil.
Is roasted leek and potato soup vegan and gluten free?
Yes, as written. It uses olive oil and vegetable stock, with no dairy, eggs or wheat. Check the stock label, since some brands contain gluten or added dairy. Chicken stock keeps it gluten free but makes it non-vegan, so pick the stock to match who’s eating.
