The kidney bean gets its name from its distinctive kidney shape and deep red color. Originally domesticated in Central America and Mexico over 7,000 years ago, kidney beans are now cultivated across the globe and are among the most widely consumed legumes. Red kidney beans are also an excellent source of plant-based protein with a strong amino acid profile — when combined with rice or other grains, they provide a complete protein comparable to animal sources. One critical safety note: raw kidney beans contain high levels of phytohemagglutinin (a lectin toxin) that can cause severe gastrointestinal distress. Always soak dried kidney beans for at least 8 hours and boil vigorously for a minimum of 10 minutes before slow-cooking. In Bulgarian cooking, red kidney beans appear in hearty stews and salads, and can substitute for white beans in traditional bean soup recipes for a colorful variation.