Gai lan is a Chinese vegetable that is also called kai lan, gailan, gai lan fa, Chinese broccoli and Chinese kale. It looks very similar to Western broccoli but with much larger leaves and smaller clusters of flower buds. A stalk of gai lan starts as a single stem that branches out, with the additional stems ending in large, dark green leaves. Toward the top of the stalk are small groups of flower buds that may be open or closed. To choose the best gai lan, inspect the stems and leaves, and look for signs of aging, spoiling or insect damage.
Choosing the best gai lan means checking the color and general condition of the stems and leaves, none of which should show any signs of wrinkling or deterioration. All parts of the vegetable, except open flower buds and the interior flesh that is visible at the cut end, should be a relatively uniform medium to dark green. The flower petals should be clean and white, without any hint of brown or gray, which are signs of deterioration. The inside flesh of the stalk should be a light green.
The cut bottoms of the stems should not have any brown spots or edges; these indicate that the stalk is old and starting to dry out. Wrinkled and cracked stems are likewise undesirable. Minor flexibility is fine, especially in thinner branches, but overall, the main stalk and all branches should be relatively firm.
Insect damage to the leaves is common. It might be difficult to avoid all insect damage, which usually takes the form of holes in the leaves, but the less damage there is, the better. The leaves should be dark green with smooth edges, and they should look clean, without dark spots.
Veins in the leaves are normally visible, and they are not a mark of age or quality. The leaves should be well formed and not limp. Yellowing leaves and flower buds are a sign that the gai lan is very old and about ready to spoil.
The main stem does not have to be very big for the gai lan to be tasty. In fact, stems that are very large in diameter can be tougher to cut and cook, with thick, tough skins. Cooks can still peel these and salvage much of the stem, but this can add up to more work than cooks might want to do. Most gai lan that is available in markets tends to be about 1 inch (2.54 cm) or less in diameter. Smaller stems cook faster and are often more tender.