10 minutes or more. Kidney beans should not be blanched for less than 10 minutes, after blanching, you need to continue to cook and simmer for about 15-20 minutes. During the process of blanching kidney beans, you can add a little cooking oil, which can maintain the bright green color of kidney beans. Kidney beans can be used to make stir-fried kidney beans, dry-fried kidney beans, kidney beans stewed potatoes and other dishes. To preserve kidney beans, you can store them in the refrigerator under cold storage.