Springtime reminds me of leeks and this soup is the perfect way to transition into milder weather and lighter meals. It’s also delicious any time you want a bowl of fresh bright garden flavors that will satisfy you on a day where a salad just doesn’t sound very good. After the leeks are sautéed in olive oil and run through a Cuisinart (or blender), we add one to two handfuls of fresh spinach and peeled green apple (Granny Smith) to the food processor, and then a few peas. These additions make our soup fresh, light, and very green, yet hearty enough without relying on common ingredients like potatoes or cream.
Store-bought chicken broth is used in this soup so the garden flavors don’t get overwhelmed–the lighter it is, the better. I add a splash of tarragon vinegar* with this broth base (chicken and tarragon make a good combination), especially when using leeks or onions. But since our leek soup is more than just a savory broth with its fresh spinach, green apple, and peas, we highlight those livelier flavors by adding both mint and thyme leaves before serving. The result is a surprisingly refreshing sensation with a hint of sweet and sour that also makes the soup very good cold (think green Borscht).
Making a batch of soup is one of the easiest ways to save time and improve nutrition. Our leek soup would work perfectly for lunch or dinner, paired with a little protein (I often add pieces of leftover chicken to mine as it warms), or as a snack. It also can be used as a light sauce plated under a grilled meat.
*Bring 2 cups of white vinegar with a handful of dried tarragon leaves (purchase a little bag where bulk spices are sold) to a near boil, turn off the heat and let cool. Allow the vinegar to sit at room temperature for several hours, then refrigerate in a sealed glass jar. Now you have an excellent tarragon vinegar that will keep for months after investing about $1.00 and less than five minutes of your time.
Cut the coarse tops off the leeks and the rooted tips.
The remaining portion of the leeks will be sliced down the middle and then run under cold water to remove any dirt (hold the leek firmly on the back side to keep it together). I chop most things in my Cuisinart to save time and wrist strain, but with leeks I give them a pre-chop by hand into 1.5 inch lengths so that the food processor blade can chop the pieces uniformly. Naturally, chopping can also be done by hand, but do small, fairly fine pieces. Use the on-off-pulse method with a food processor, letting the leeks sit for a second between chops. That way they don’t turn to mush. It took me about 2 minutes to chop my leeks and rinse out my food processor. You can’t chop leeks in a regular blender, but may use it after your leeks are cooked when you add in some broth.
Add the chopped/sliced leeks to a stainless steel or non-stick skillet (cast iron will brown them too much), with 3 T olive oil and sauté until the leeks soften.
I stop cooking right as the color begins to go from green to a yellow, which is about 8 minutes on medium heat. Keep a steady stir on the leeks and don’t overcook, but do have them tender enough for your liking.
The leeks in the photograph need about another minute of sauté to soften. The soup gets no more “cook time,” than this sauté step, although once the leeks are pureed or processed they will soften further. Because I like my cooked leeks to retain some of their bright color, I often add my splash of vinegar while the green is still visible so the color sets a bit. Don’t worry if they yellow–there’s spinach to correct the color.
At this point ½ the leeks can be added into your food processor with enough broth put in after the leeks (about a cup) to the food processor so the liquid doesn’t seep out the bottom. If you are using a blender do just the opposite, liquid first (and use more–1 ½ cups) then leeks. Turn your machines on to make a puree then add the remaining leeks and enough broth for the leeks to completely mix in uniformly.
Peel and chop your apples into one-inch pieces. Add those to the food processor or blender. Now pour in a about another ½ – 1 cup of broth (blenders will always need a little more liquid than food processors) and puree again. Put the two handfuls of spinach into your food processor or blender (one handful at a time for the blender) and incorporate into the puree, adding broth as necessary. Ultimately more broth will be added once the finished puree is returned to the pan on the stove, or into a soup pot to warm.
And finally….add those peas. Warm the peas for a minute in a microwave or run under hot water if they are not completely defrosted. They mix in better once warmed. Peas get starchy if overworked in a food processor or blender, so don’t let it run long once they are added. If you care to make sure every single pea really gets smooched up, then mash them a bit in a bowl with a fork before they go into your machine. Again, add broth as necessary.
Your soup is almost ready, now it’s time to fine tune those flavors. Return your mixture to the stove (I just use the large sauté pan I cooked the leeks in) in a pan that has enough room for you to stir in more broth and season the soup without risk of going over the edges. Add broth to get to your desired consistency and begin to warm.
If you didn’t do so earlier, add in the 2 Tblsp of tarragon vinegar, salt and pepper. Next, finely chop the mint leaves, starting with about 1 Tblsp and add along with 1-2 tsp of thyme leaves stripped from the woody branches. I usually put in 1-2 Tblsp of mint, or 6 medium-sized leaves, but it’s a matter of personal preference. Taste after 1 Tblsp. when you have added the salt and pepper. Squeeze in some lemon juice as the last step to brighten further. About 2 tsp should do it. There, it’s done.
Note: This soup thickens up, so when you reheat it add either broth or water to get your desired consistency.
Don’t underestimate the ability of a little lemon juice or extra pinch of salt to make a soup with fresh flavors really come alive. Taste as you go, adding small amounts of each at the very end. And don’t forget to include some black pepper, too.