3 to 5 minutes. Soak the washed kidney beans in cold water for 10 minutes to allow them to absorb water, then blanch them in boiling water for 3 to 5 minutes. When the kidney beans become brightly colored and soft, take them out and cool them in cold water to retain them. Crisp and tender texture. The blanching time should not be too long, otherwise the taste and nutrients of the kidney beans will be destroyed.