Why some vegetables stay bright green comes down to chlorophyll, heat, water, and acidity. Brief steaming or quick blanching usually keeps beans, broccoli, peas, and spinach vivid, while overcooking and early acid addition push them toward olive or dull tones.
Essential Concepts
Chlorophyll gives green color.
Steam preserves best.
Boiling and acid dull faster.
Overcooking causes most color loss.