Both bok choy and choy sum are ubiquitous in Asian markets, and to the untrained eye, they might look interchangeable. However, understanding their differences in appearance, flavor, and texture is key to using them correctly in your cooking. While both belong to the mustard family (Brassica), they are separate varieties with unique characteristics that make each suited for different culinary purposes.
Bok Choy: The Spoon Cabbage
Bok choy, also known as pak choy, is one of the most widely recognized Chinese greens. Its Cantonese name, pak choi, means 'white vegetable,' a reference to its characteristic white stems.
Appearance
- Stems: Mature bok choy has thick, crunchy, white stems that form a compact, head-like base. Baby bok choy is smaller, with light green leaves and stems.
- Leaves: The leaves are dark green and shaped like a spoon, with ruffled edges.
- Growth: The vegetable grows in an upright bunch or head.
Flavor and Texture
- Flavor: It has a mild, slightly sweet, and peppery taste. The white stems are sweeter and crunchier, while the dark green leaves have a softer texture and a slightly more bitter note.
- Texture: The stems offer a distinct crunch, providing a contrast to the tender, quick-wilting leaves.
Culinary Uses
Bok choy is incredibly versatile and well-suited for a variety of cooking methods that can handle its dual textures. The leaves cook faster than the stems, so separating them during prep can ensure even cooking. It is often stir-fried, braised, steamed, or added to soups.
Choy Sum: The Flowering Vegetable
Choy sum, often called Chinese flowering cabbage or yu choy, is another popular Asian green prized for its tender stalks and edible flowers. Its name translates to 'vegetable heart' in Cantonese, referring to the tender central stems.
Appearance
- Stems: Choy sum has slender, pale green stems that are more delicate than bok choy's.
- Leaves: The leaves are large, oval, and dark green.
- Growth: Unlike bok choy, it grows as individual, leafy stalks and develops small, bright yellow flowers at the top when mature.
Flavor and Texture
- Flavor: Choy sum has a sweet, tender flavor with a subtle hint of mustardy bitterness that is more pronounced than bok choy's. The small yellow flowers are also edible and have a pleasant taste.
- Texture: The entire vegetable is tender, and the delicate stems cook quickly to a tender-crisp consistency.
Culinary Uses
Because of its delicate structure, choy sum is best used in fast-cooking applications. It is frequently stir-fried with garlic or blanched and served with an oyster sauce dressing as a side dish. It's a key ingredient in many Chinese dishes where its tender texture is a highlight. The Woks of Life provides great insight on its culinary profile.
Comparison Table: Bok Choy vs. Choy Sum
| Feature | Bok Choy (Pak Choi) | Choy Sum (Yu Choy) |
|---|---|---|
| Appearance | Thick, white or light green stems; dark, spoon-shaped leaves in a compact head | Slender, pale green stalks; large, oval leaves; small, yellow edible flowers |
| Flavor | Mild, sweet, and slightly peppery; stems are milder and sweeter than leaves | Sweet with a slight mustardy bitterness; flowers also edible with a delicate flavor |
| Texture | Crunchy, juicy stems and tender leaves | Uniformly tender stalks and leaves |
| Cooking | Good for stir-fries, braising, and soups; stems require longer cooking time than leaves | Ideal for quick stir-frying, steaming, and blanching; entire vegetable cooks quickly |
Nutritional Similarities and Health Benefits
Despite their differences in taste and texture, bok choy and choy sum are nutritionally similar powerhouses. As with many Asian greens, both are excellent sources of vitamins A, C, and K, and provide a good amount of folate, calcium, and potassium. They are also low in calories and fat. The high vitamin and mineral content contributes to overall health, supporting bone health, immune function, and protecting against chronic diseases. While minor variations exist, incorporating either into your diet is a great way to boost nutrient intake.
Cooking and Substitution Tips
Knowing the differences between these two greens helps when cooking. For instance, in a quick stir-fry, choy sum’s uniform tenderness means you can toss the whole vegetable in at once for a short period. For bok choy, it's often best to separate the thick stems from the leaves, cooking the stems for a minute or two before adding the leaves to prevent them from becoming overcooked and soggy.
Can they be substituted? Yes, with mindful adjustments. If using bok choy for a choy sum recipe, dice the stems finely to match the quicker cooking time. If replacing bok choy with choy sum, you can add all the choy sum at once towards the end of the cooking process to preserve its delicate structure.
Conclusion: Making the Right Choice
Ultimately, the choice between bok choy and choy sum depends on the desired flavor and texture for your dish. If you prefer a milder, sweeter flavor with a mix of crunchy and tender textures, bok choy is the right pick. Its hearty stems can stand up to longer cooking times in soups and stews. If a dish calls for a quick, delicate green with a touch of mustardy bitterness and uniform tenderness, choy sum is the ideal choice for stir-frying or steaming. Both are delicious, versatile greens, but their subtle distinctions offer different experiences in the kitchen.
Foraging for the Perfect Asian Green
- Check the Stems: Look for bok choy with crisp, firm white or light green stems and choy sum with slender, pale green stems.
- Look for Flowers: Choy sum is often identifiable by its small, edible yellow flowers. Bok choy does not have these.
- Inspect Leaves: Choose greens with vibrant, dark green leaves that are free from yellowing or wilting, indicating freshness.
- Consider Maturity: Baby bok choy will be more tender than mature bok choy and have lighter green stems.
- Cook Separately: When preparing bok choy, remember that the stems and leaves have different cooking requirements; add the stems to the pan first.
- Quick Cooking: Preserve the delicate texture of choy sum by using quick-cooking methods like steaming or stir-frying.
Comparison of Different Types of Asian Greens
- Kai Lan (Chinese Broccoli): Related to both bok choy and choy sum, gai lan has thicker, flatter stalks and a more pronounced, bitter-sweet flavor. It requires slightly longer cooking than choy sum.
- Tatsoi: Often mistaken for a type of bok choy, tatsoi has very dark green, spoon-shaped leaves that form a low rosette. It has a mild flavor and is tender enough for salads.
- Yu Choy: This term is often used interchangeably with choy sum, particularly in reference to the plant sold for its tender shoots and flowers.
These varieties, along with bok choy and choy sum, offer a world of flavor and texture for home cooks to explore.
Conclusion
In summary, there is a clear difference between bok choy and choy sum, spanning their appearance, flavor, texture, and ideal cooking methods. Bok choy, with its sturdy white stems and spoon-shaped leaves, is best for heartier cooking, while choy sum, with its slender stalks and tender flowers, is perfect for quick, delicate dishes. Understanding these nuances allows you to select and prepare the perfect green for any recipe, enhancing the flavor and authenticity of your Asian-inspired meals. Next time you are at the market, look for the yellow flowers to identify choy sum or the thick white stalks for bok choy, and you'll know exactly what you're getting.
