Ratios & Conversions

Chinese Ratios

Sweet-and-Sour Sauce (Vinegar to Sugar to Soy to Ketchup)

Also: 糖醋汁比例, tang cu zhi ratio, Chinese sweet-sour sauce

The 1:1:½:½ sweet-sour framework — rice vinegar, sugar, ketchup, and soy sauce — that produces the glossy, tangy coating for Cantonese sweet-and-sour pork and countless wok sauces.

Chinese sweet-and-sour sauce (糖醋汁, táng cù zhī) is a pantry sauce built on balanced tartness and sweetness, with soy sauce for depth and ketchup for colour, body, and a background tomato-fruit note. A cornstarch slurry is always added to convert the thin liquid into a clinging, translucent glaze. The ketchup component is a 20th-century Cantonese adaptation that replaced earlier versions made with fresh tomato or plum sauce; it now dominates restaurant practice worldwide because it contributes both colour and viscosity efficiently.

The proportions

1 part
Rice vinegar (米醋) — Chinese rice vinegar is milder than Western wine vinegar (about 4.5% acetic acid); do not substitute undiluted cider vinegar without reducing the quantity.
1 part
Sugar (白糖 or 冰糖) — White granulated or rock sugar; rock sugar makes the finished glaze slightly more translucent.
½ part
Ketchup — Adds tomato umami, pectin body (reducing the starch needed), and the orange-red colour. Heinz or equivalent; avoid 'low-sugar' versions as they thin the sauce.
½ part
Light soy sauce (生抽) — Provides saltiness and umami; prevents the sauce from reading as purely sweet-tart.
1 Tbsp starch per 100 ml sauce
Cornstarch slurry (1:2 starch to water) — Stir in at the end over medium heat until the sauce turns glossy and clings to a spoon.
2 Tbsp per 100 ml
Pineapple juice (optional) — Traditional in Cantonese gū lǎo ròu; adds tropical acidity and bromelain tenderising.

Method

Combine rice vinegar, sugar, ketchup, and soy sauce in a small bowl and stir until sugar dissolves. Pour into a wok or saucepan over medium-high heat and bring to a simmer. Taste and adjust: if too tart, add sugar in small increments; if flat, add a few drops more vinegar. Stir in the cornstarch slurry gradually, whisking constantly until the sauce turns glossy and coats the back of a spoon. Toss immediately with the prepared protein or vegetables.

Tips

  • Dissolve the sugar in the cold vinegar before heating — undissolved sugar can scorch before it melts uniformly.
  • Add the cornstarch slurry off the heat or at a low simmer; high heat gelatinises starch instantly, creating lumps before it distributes.
  • Ketchup's pectin means you need about 20% less starch than in a no-ketchup version — over-starching produces a gluey, opaque sauce.
  • Taste for balance before slurry: the sauce should be aggressively sweet-tart at this stage because the starch will mute the flavours slightly as it thickens.
  • Use immediately once thickened — cornstarch-based sauces thin on standing as starch granules rehydrate; they do not hold well for service.

Variations

  • Plum-based (preindustrial Cantonese)

    Replace ketchup with Chinese plum sauce (suanmei sauce); the result is more stone-fruit forward and darker.

  • Fujian version (lychee sauce base)

    Adds canned lychee syrup and a squeeze of lemon; slightly floral, common in Fujian and Taiwanese restaurants.

  • Shanghainese tang cu (糖醋里脊)

    Higher vinegar-to-sugar ratio (3:2) for Shanghainese crispy pork strips; soy reduced to a few drops; ketchup often omitted.

  • Guotie dipping sauce

    Thin the base 1:1 with water, omit ketchup, add chilli oil — used as a pot-sticker dipping sauce.

  • Westernised restaurant version

    Higher ketchup proportion (equal to vinegar) and a touch of Worcestershire; thicker texture, more familiar to non-Chinese diners.

Related ratios

Appears in

Gū lǎo ròu — Cantonese sweet-and-sour pork (古老肉)Sweet-and-sour crispy fish (糖醋鱼)Shanghainese tang cu pork ribs (糖醋排骨)Sweet-and-sour prawns (糖醋虾)Spring roll dipping sauce

References

  1. 1.The Complete Chinese Cookbook — Ken Hom
  2. 2.Every Grain of Rice — Fuchsia Dunlop
  3. 3.Chinese Cookery — Deh-Ta Hsiung

Confidence: high

Notes

Why ketchup replaced tomato paste

Early 20th-century Cantonese restaurants in Hong Kong began substituting ketchup for fresh tomato and plum sauces because ketchup provided instant colour, consistent acidity, and binding pectin in a single ingredient. The substitution proved so practical that by mid-century it had become the canonical ingredient even in home cooking — a rare case of a convenience product improving on the original's convenience without sacrificing flavour.

Viscosity vs. transparency

The ideal sweet-and-sour glaze is glossy and just barely transparent, showing the colour of the meat beneath. Over-adding ketchup or starch makes the sauce opaque and dull. The two-step approach — ketchup for pectin body, starch for final sheen — threads this needle: the ketchup's natural viscosity reduces starch demand, and a lighter starch addition preserves translucency.