Identify the role of black bean sauce in your dish (stir-fry glossy base, marinade depth, or baked umami).
Choose the closest match from the ratio table: fermented black bean paste first, then soy+miso, then oyster/hoisin for sweet-umami profiles.
Use the listed ratio; if your substitute is thicker than black bean sauce, thin with 1–2 teaspoons water at a time.
Taste and fine-tune in small steps: add salt (soy) for more savor, or balance sweetness (less hoisin/teriyaki, or reduce sugar additions).
For stir-fries, briefly simmer the sauce in the pan (15–45 seconds) to round flavors before serving.