Creamy Potato Leek Soup with Asparagus and Spinach Oil-Free

A gentle soothing and satisfying creamy soup that celebrates the lush green flavors of spring. Make it your own by using your favorite combination of fresh garden herbs. Like a ray of sun after a spring rain, lemon juice brightens the mood of this nourishing soup.

WHY I LOVE IT

This recipe has everything I want from a green creamy soup. And it just so happens that potatoes and asparagus are my top two favorite vegetables. I love the glossy sheen of creamy soups thickened with potatoes. The classic potato and leek combination makes for a wonderful backdrop to the delicate flavor of asparagus. Baby spinach contributes a visually appealing intensely green color while boosting the overall nutritional content. I grow my own herbs year round and love experimenting with different combinations. But if you don’t grow your own herbs, and don’t want to pay an arm and a leg for them at the store, don’t worry because dry herbs can also work well in this soup. This is a versatile recipe. I’ve used zucchini in place of asparagus and almost any green leafy vegetable can be used as a substitute for baby spinach.

PEELING POTATOES IS OPTIONAL

When cooking with potatoes, I usually don’t peel them. Potato peels are a great source of fiber and nutrients so I’d rather keep them on. I’ve discovered that using clean unpeeled potatoes in creamy soups does not detract from the creaminess. But if you are bothered by leaving peels on for any reason, then peeling your potatoes for this soup is also fine. It’s entirely up to you!

WASHING LEEKS

Leeks can be one of the most difficult vegetables to clean if you approach cleaning them like you do most vegetables. Tiny dirt particles have a way of getting trapped between the layers, and it’s nearly impossible to get all that dirt out when leeks are whole. Getting everything nice and clean before prepping is the logical order of things for most vegetables. But with leeks it’s easier and more effective to trim and chop your leeks before washing them.

Start by removing the parts you won’t need. For this recipe you only need the white and tender light green portions. Roots and dark green tough leaves should be removed. You can save the dark green leaves for making homemade vegetable stock.

Slice unwashed leeks to the size needed for your recipe and place them in a bowl that’s large enough to hold twice the amount of volume than your leeks take up. In other words, if you have a cup of sliced leeks, your bowl should hold at least two cups. Bathe leeks by pouring water over them when they’re in the bowl. Using your fingers, agitate the leek slices in the water so that trapped dirt is released into the water, then strain. Return strained leeks to the bowl, cover them with water again and repeat the process. You usually need to bathe, agitate and strain leek slices three times to get all of the dirt out.

ASPARAGUS SAYS SPRING ANYTIME

No vegetable makes me think of spring more than asparagus. I live all the way up in Washington State, so our season for fresh local asparagus goes on almost to the end of June. Of course we start seeing asparagus from California when it’s not even spring yet, and Mexican asparagus is usually available year round. But here’s the thing, if you want to use frozen asparagus, or any other frozen veggie in this soup, go for it. Frozen vegetables are economical and convenient. Creamy soups are one of the best places to use frozen vegetables. The freezing process stretches and weakens the cell membranes of vegetables making them mushier. But for creamy soups mushiness is not a bad thing, so proudly use frozen vegetables if you’d like. Combining fresh and frozen ingredients works particularly well.

YOU CAN USE ZUCCHINI IN PLACE OF ASPARAGUS

In this particular recipe zucchini is a wonderful substitute for zucchini. It’s easier to find good fresh zucchini year round. Although the flavor profile of the soup will be different, it will have the same refreshing and mildly sweet taste. I love making this soup in late summer or early fall using fresh zucchini from my garden. Use an equal amount of zucchini to the amount of asparagus in the recipe. Though nothing in this soup needs to be exact, 12 ounces of zucchini is about 1-3/4 chopped.

A LEAFY HERBAL BOUQUET

My favorite herbal bouquet for this soup is a combination of celery leaves, parsley, thyme and mint. I am not currently growing my own celery, but all of the other herbs came fresh out of my garden in early June when I was writing this recipe. And they all contrast beautifully against the bright citrusy taste of lemon. You can use any herb combination you like in this recipe, or keep it simple and use just one herb.

Whenever possible I like to find celery with plenty of leaves. Celery leaves are considered an herb in their own right. They impart a fresh intense celery taste that’s a little different than the flavor of celery stalks. To use celery leaves in this recipe, separate them from the stalk and set them aside. You will add them in along with the other fresh herbs during the last step of the recipe.

You can use dried herbs instead of fresh herbs and this soup will still be delicious. When substituting fresh herbs with dried herbs remember to use half the amount. Also dried herbs and fresh herbs are added to recipes at different times. Fresh herbs are almost always added at the end of the cooking process while dried herbs are usually added earlier.

EARTHY UMAMI WITH MUSHROOM POWDER

Mushrooms can contribute a depth of umami flavor that we usually associate with animal foods. I love cooking with fresh and dried mushrooms. I’m even a fairly skilled mushroom hunter. But it’s often the case that I want to bring some umami mushroom goodness into my cooking without introducing the texture of mushrooms. And that’s where culinary mushroom powders come in.

Almost any culinary mushroom powder would be acceptable in this recipe. I prefer to use shiitake mushroom powder because it’s the most subtle and thus the most versatile. But porcini powder and lion’s mane powder are also amazing, though they have a stronger, less creamy, flavor. It’s worth investing in mushroom powders as pantry staples. Using them sparingly, adding little bits here and there in your cooking, can take savory plant-based dishes to another level. Mushroom powders can blend in with other flavors inconspicuously when used in moderation. Shiitake mushroom powder happens to be the least conspicuous and the best at highlighting the umami notes present in adjacent ingredients.

But these powders have benefits that go beyond flavor. Shiitake mushroom powder is a perfect example. I would be in mad love with shiitake mushroom powder even if it wasn’t as ridiculously good for you as the research says it is. Think vitamins, minerals, immune function, weight loss and more. You can google the scientific good-for-you part, if you’re interested.

EASY PEASY OIL-FREE SAUTÉING

It took a while for me to embrace the idea that you can sauté your food without using any oil. Even when I was already completely on board with the whole food plant-based life style philosophy, I felt like being 100% oil-free was for people who had non-stick pans, not for someone like me who prefers cast iron skillets and ceramic pots. So for a long time I kept using little bits of oil at the beginning of my sautéing process and then adding small amounts of water when things began to stick. I still use this hybrid method for some things, but I’m realizing that that little bit of oil at the beginning is not really necessary. In fact, if you want a teaspoon or two of oil because you love the flavor of certain oils (think extra virgin olive oil or toasted sesame oil), you’ll get much more from your oil if you use it as a finishing oil in the final step of the recipe than at the beginning when you’re heating it up. But I digress.

Although this is a soup where eventually most of the ingredients are simmered together for an extended amount of time, I still like to sauté the leeks, celery and garlic first in order to build flavor through caramelization. And yes, caramelization still happens when you’re not using oil for sautéing. I also like to add in the asparagus during the final stage of sautéing to maximize the flavor.

For this recipe, I usually use vegetable stock for sautéing but water works perfectly well too. In any case, you don’t need very much liquid because leeks and celery release a lot of their own water as they cook.

Begin by heating approximately 2 tablespoons of vegetable stock or water in a large pot over high heat. Keep more water or stock close at hand to use as needed. When the liquid in the pot comes to a rolling boil, add leeks, celery and garlic. Sauté for about 4 minutes or until soft and tender but not browned, adding little bits of liquid as needed to keep the veggies from burning as they inevitably begin to stick to the pot. That momentary sticking without burning is what you want because it means that caramelization is taking place. Then add the asparagus and sauté an additional 2 or 3 minutes, adding small amounts of liquid as necessary. Now you’re ready to add in your vegetable stock, potatoes, mushroom powder and any dried herbs you may be using.

IMMERSION BLENDER RECOMMENDED

In order to create a creamy texture, you will need some sort of blender or food processor. An immersion blender is especially good for soups because it saves you the trouble of taking cooked ingredients out of the pot and into another container for processing.

After checking to make sure all the vegetables are fork-tender, turn off the heat and add the spinach and herbs. When the spinach is fully wilted and bright green, dip the immersion blender into the soup and process until smooth.

You could make this soup using a stand alone blender or food processor instead, but it’s a bit of extra work because you would have to let the soup cool a bit first then run it through in batches. Another way is to strain out all the vegetables, purée them separately from the rest of the broth, then mix them back into the broth and reheat.

Whichever puréing method you use, it’s crucial that all the vegetables be completely soft before processing or you’ll end up with a hopelessly gritty soup. When the soup is as smooth and creamy as you want it, squeeze in some lemon juice, adjust seasonings, and serve!

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