Glossary - Ingredients

Komatsuna / Japanese Mustard Spinach

A nutritious green leafy vegetable with a mild taste, suitable for use in a variety of dishes

What is komatsuna?

Komatsuna / Japanese mustard spinach (こまつな in Japanese) is a green leafy vegetable native to Japan. It has a mild taste and is widely used in ohitashi (a side dish of greens in bonito-flavored soy sauce), stir-fries, simmered dishes, miso soup, and clear soups. It has long been an indispensable ingredient in Kanto-style ozōni, a soup to celebrate New Year’s containing rice cakes, vegetables and more.

Kanto-style ozōni with komatsuna

Nutrition facts

Komatsuna is rich in calcium, potassium, iron, beta-carotene, vitamin C, vitamin K, niacin, and folic acid. Recognized for its nutrient content, komatsuna is particularly high in calcium, containing about three times the amount of spinach. This leafy green also contains vitamins B1 and B2, which promote metabolism, and is a good source of dietary fiber.
As for phytochemicals, komatsuna contains lutein, which promotes eye health. Furthermore, komatsuna is low in oxalic acid, a compound known to cause kidney stones, making it suitable for eating raw.
As it contains a lot of fat-soluble vitamins, cooking komatsuna with oil or eating it with foods that contain fats and oils promotes nutritional absorption. Eating komatsuna with soy products such as aburaage / thin deep-fried tofu, and other protein sources such as meat and fish, is also beneficial for promoting bone health and preventing anemia.

Storage to prevent food loss

Wrap komatsuna in moist kitchen paper and place in a plastic bag in the refrigerator for storage for 2 to 3 days. In the case of freezing, cut raw or boiled komatsuna that has been squeezed well to remove excess moisture into bite-sized pieces, then store in a plastic bag in the freezer for up to about 1 month.

Trivia

When raw frozen komatsuna is thawed naturally, the fibers break down and are softened, so by pouring soy sauce or tsuyu (noodle soup base) over top, you can prepare ohitashi.

Cooking Basics

Greens - making a cross cut into the root

As the thick root takes longer to cook through, make a cross cut into the root to allow for faster cooking. This will also allow water to be absorbed more easily to increase crispiness.

Greens - soaking in water to revive

If the greens themselves are in good condition, they will have good texture when used in stir-fried and simmered dishes. Also, this step allows dirt trapped in the roots to be removed naturally.

Greens - separating leaves and stems

The cooking time required for stems and leaves differs. When you want to quickly saute or boil, stems and leaves need to be cut apart and added in at different times. First add in the stems, and once softened, add in the leaves to allow for even cooking.

Greens - boiling in salt

Add salt to plenty of boiling water to achieve salt concentration of about 1 - 2%, then add in the greens from the roots. After boiling for about 20 seconds, remove into cold water.