Spring onion
The white and the green are effectively two ingredients: one is an aromatic you fry in fat, the other is a garnish you add at the end.
White and green are different ingredients
- The white (root end) β firm and strongly aromatic. This is what you fry in fat for flavour. It is the part used to make scallion oil, and the base of dishes like Jjajangmyeon.
- The green (leaves) β soft and lightly aromatic. Long cooking drives the aroma off, so it goes in at the end, or on top raw. Ramen, Gyudon, finishing a soup.
Even when a recipe just says "1 spring onion", use the white for frying and the green for garnish.
Scallion oil
Cook the white parts gently in oil and the aroma transfers to the fat; lift them out once browned and cook with the oil. It is a foundation of Chinese stir-frying, and it works because aroma compounds are fat-soluble β see Blooming spices.
How to cut it
- On the bias β soups and braises. More surface area, more aroma released.
- Thin rounds β garnish, dressed dishes.
- Fine shreds β for serving raw. Five minutes in cold water takes the bite off and crisps them.
Choosing and cleaning
Long, firm whites and leaves that are not wilting. Peel off the outer layer at the root end. Grit gets between the leaves, so split them lengthwise and rinse under running water.
Storing
- Fridge β wrapped in damp paper towel and sealed, one to two weeks.
- Freezer β sliced and sealed, three months. The crunch goes but they are fine for soups and stir-fries, straight from frozen. See Freezing and thawing.
- Trim off only the yellowed leaf tips; the rest is still good.
Substitutes
- Onion β for the white part; different aroma, noticeably sweeter.
- Leek β closest to the white, milder.
- Chives β the nearest thing to the green part.