If you have ordered sashimi and found a small bundle of long white stems with tiny green leaves at the side of the plate, you have met kaiware (かいわれ), the radish microgreen. In Japan it is as familiar as bean sprouts are in Thailand. Here is what is worth knowing before you buy, plus the basics if you want to grow some yourself.
What is kaiware?
Kaiware is the seedling of the radish (Raphanus sativus), cut a few days after sowing, just as its first two seed leaves open. The full Japanese name is kaiware daikon (貝割れ大根). Kaiware means "split shell": the two seed leaves spreading apart look like a clam that has just opened.
White kaiware comes from ordinary Japanese daikon, with ivory stems and green leaves. Red kaiware comes from a radish variety with pink-red stems. The colour is anthocyanin, the same family of pigment that makes red cabbage purple.
How it tastes, and how Japanese and Thai kitchens use it
Kaiware is crisp and juicy with a light, peppery radish heat that fades quickly rather than lingering like chilli. Red kaiware is a little hotter than white and stands out more on the plate. The heat comes from glucosinolates, compounds found across the cabbage family: when you chew, an enzyme in the plant cells turns them into pungent compounds, the same kind of reaction that gives wasabi and mustard their kick.
In Japanese cooking kaiware is an everyday garnish: beside sashimi, in temaki hand rolls, on chilled tofu (hiyayakko), natto or cold soba, in miso soup once the heat is off, and in egg sandwiches.
It suits Thai food just as well. Try it in yam woon sen or a salmon yam in place of some of the coriander, roll it into fresh salad rolls, scatter it over fried rice or a Thai omelette on rice to cut the oil, or add it to a clear soup once the heat is off (see our tofu and minced pork clear soup with kaiware). The rule is simple: add it last. Long cooking softens the stems and takes the pepperiness away.
What's in kaiware
Kaiware contains vitamins A, B, C, E and K, along with minerals such as calcium, iron and magnesium. A US Department of Agriculture study of 25 microgreens (Xiao et al., 2012) found that most carried higher concentrations of vitamins C, E and K and carotenoids than the same vegetable at maturity, and that among the microgreens tested, green daikon radish had the highest vitamin E (tocopherol) content.
The actual amounts in any box depend on the variety, the age at harvest and how it has been stored. This is general information about what the food contains, not medical advice.
Choosing a good box, and keeping it crisp
When you buy, look for:
- Stems that stand upright and firm, not bent over or limp.
- Seed leaves fully open and bright green, not yellow or spotted, with clear pale stems on white kaiware and an even pink-red on red.
- A dry box, with no water pooled at the bottom and nothing slimy.
- A fresh, green smell, not sour or musty, and a recent packing date. The newer the box, the crisper it is.
A few seed hulls clinging to the leaves are normal for any seedling; brush or rinse them off.
At home, put the box straight into the fridge, in the vegetable drawer or on a lower shelf, standing upright so the long stems do not crush each other. Don't wash it yet; rinse only what you are about to eat. Wipe any droplets inside the lid with a paper towel and close it again. Kaiware keeps about 7–10 days, though it is crispest in the first few.
Can you grow them at home?
Yes. Radish is one of the easiest microgreens for a beginner, because the seeds are large and sprout quickly. The basics:
- Use a shallow tray with drainage holes. Fill it with 2–3 cm of clean seed-starting mix, or use a grow mat made for microgreens, and water until moist but not soggy.
- Buy seed sold for sprouting or microgreens, which is not coated with fungicide. Soak it for 4–8 hours so it germinates evenly, or sow it dry.
- Scatter the seed thickly but in a single layer, then mist it.
- Keep it dark for 2–3 days under an upturned tray or a cloth, while the roots take hold and the stems stretch.
- Uncover it and set it near a bright window, out of harsh afternoon sun. The leaves turn green within a day or two.
- Water once or twice a day, ideally into a tray underneath, so the leaves stay dry and mould is less likely.
- Harvest when the seed leaves are fully open and before the first true leaves appear. At Thai room temperature that is usually about 5–7 days. Cut just above the growing mix with clean scissors, rinse, and eat.
Around day two or three you may see white fuzz around the roots. Those are root hairs, not mould; mist them and they collapse. Real mould looks like cobweb spreading over several seedlings and smells musty. Our hot, humid weather makes mould easy, so keep the tray where air moves and never let it sit waterlogged.
If you would rather have long, even kaiware without the wait, order Dr.Sprouts white and red kaiware on LINE @dr.sprouts, 60 THB a box. Our team will confirm the delivery round in the chat.
Sources
Note: Nutrition notes are drawn from the cited research and are general information, not medical advice.
