Monday, March 6, 2017

Japan: Miso Soup and Japanese Sweet Potato

I'm a creature of habit, and what that means is, I pretty much eat the same lunch every day. Today's post is about that lunch. I've been eating this most days for the last 18 to 20 months.

It's Miso soup and a Japanese sweet potato topped with ginger root. These are foods that the Okinawan population ate on a regular basis. And according to Blue Zones author, Dan Buettner, the Okinawan population is the second longest living population in the world (the first longest living being the Seventh Day Adventists in Loma Linda, California). Much of their health and long lifespan has been attributed to their diet, although there are other factors that played into it as well.

Before giving specific recipes, let me address Miso for a minute. Many people have concerns about Miso because of its sodium content. And if you're one of them and you still have that concern after reading what I'm about to say, you can leave the Miso out of this soup. The soup is chock full of nutrients and antioxidants even without the Miso. So, if you're concerned about that, just follow the recipe and at the end, don't add the Miso.

The concerns about Miso are the high sodium content, which can lead to stomach cancer or high blood pressure. Dr. Michael Greger has addressed the concerns about Miso in this video titled Is Miso Healthy? As Dr. Greger explains, a recent study found, with respect to blood pressure, that a person had five times the lower risk of high blood pressure if they ate two or more bowls of Miso soup each day. Dr. Greger explains that the soy in Miso soup (from the tofu) can be counteracting the high sodium's effect on blood pressure. And according to The Miso Book by John Belleme and other things I've read, Miso is also high in potassium and potassium actually acts to lower blood pressure. So, perhaps the soy and the potassium working together make hypertension an unlikely result from eating Miso soup. I know from my own personal experience that eating Miso soup on a daily basis has not adversely affected my blood pressure, which averages around 110/70 without any prescription medicines. That's considered remarkable for a 70 year old man.

Dr. Greger also cites studies showing that the salt in Miso soup, unlike the salt in processed foods, has had no effect on stomach cancer rates. Dr. Greger talks more about this on pages 280-281 of his most recent book, How Not to Die.

Regarding the Japanese sweet potato, if you've never had one, you are in for a treat. They are a little pricey when compared to a regular sweet potato or to a yam, but they are well worth it. I buy mine at Whole Foods Market as many regular grocery stores don't carry them. The Japanese sweet potato has a purple skin, but the inside pulp is white. So it should not be confused with a purple sweet potato, which is purple all the way through (and good too). Once cooked, the Japanese sweet potato has a wonderful creamy texture to it. I doubt that you'll be disappointed. So, don't settle for just an orange sweet potato all the time. Give a Japanese sweet potato a try. I think you'll be pleasantly surprised.

Here are the recipes for my daily lunch.

Japanese Sweet Potato

Serves one


1 Japanese Sweet Potato
Sprinkling of Ginger Root


Because of the lengthy cooking time for the Japanese sweet potato, you will want to start this approximately three hours before you plan to actually eat.

The only way to cook a Japanese sweet potato in my opinion is to do it in the Instant Pot or other pressure cooker. Place approximately 3/4" of water in the bottom of the liner pan and put in a steamer basket. Then place the Japanese sweet potato in the middle of the pot and cook under pressure for two hours. Note that two hours is considerably longer than you would cook a standard sweet potato for, but the longer you cook a Japanese sweet potato, the better it is (both taste-wise and consistency-wise).

Once cooked, let the pressure come down naturally and then cut the potato lengthwise and mash up the inside of the potato. Sprinkle with the ginger root and enjoy along with the Miso soup. 

As an alternative, I will oftentimes drizzle apple cider vinegar over the Japanese sweet potato before eating. Then I may or may not add the ginger root. Each way has its own unique taste, and they're all delicious.

Miso Soup

Making Miso soup is a little less exact. There are definite ingredients that should go in all Miso soups. And then there are optional ingredients that I will add at different times. So, every version of Miso soup that I make is different. Here are some ideas for making Miso soup. In general, I fill the pot and consider what I make to provide 4 to 6 servings.


1 large onion, quartered or 2 bunches spring onions, chopped
1 large garlic, minced
10 oz. Shitake mushrooms (I will sometimes mix in oyster, crimini and portobello mushrooms)
16 oz. Extra Firm Tofu, cut into 1/4" squares
4 to 6 carrots, sliced
1 bunch asparagus and/or 1 package frozen veggies of choice and/or fresh veggies of choice
5 ounces of Wakame or Kale (if kale is used, then also add a 6" square inch piece of Kombu)
8 cups (or more depending upon how thick you like your Miso soup) of vegetable or Miso broth
1 tablespoon / serving of Red Miso


Place all ingredients except the Miso in a large pot, cover and bring to a boil and then simmer on low for 30 minutes. Alternatively, the Instant Pot can be used. Just put all the ingredients except the Miso into the Instant Pot and cook under pressure for 0 (zero) minutes. Just be careful to do a natural pressure release. This recipe fills up the Instant Pot and you will spray liquid soup all over your kitchen counter and ceiling if you try to release the pressure too early (I know this from personal experience).

Remove the kombu before placing the soup in bowls.

When you're ready to serve the soup, place the soup in bowls and then add 1 tablespoon of Miso to each bowl. Stir well to mix the Miso into the soup.

Do not cook the Miso. The active cultures in Miso that makes it so healthy for our guts are destroyed when boiled. Therefore, in order to get the health benefits of this meal, it is best to add the Miso when ready to eat. Because of that, using Miso broth is not a substitute for using Miso. The reason for using Miso broth is simply for taste.

For the Miso soup in this picture, I also added a sprig of fennel (or anise) to the soup. I've also added mint leaves and Sriracha sauce in the past as well. And sometimes, I've topped my Miso soup with unsalted peanuts. The possibilities are endless and totally up to you. Like me, you don't have to do it the same every time. Variety can be the spice of life.

© J Lanning Smith
March 6, 2017

1 comment: