Whether you slice it, dice it, mash it or puree it, avocados are a healthful addition to your diet, as long as you eat them in moderation. A serving of avocado contains more potassium than a banana and also contains healthy doses of magnesium, folate, vitamins C, B6 and E, fiber and healthy monounsaturated fats, the Centers for Disease Control and Prevention reports. The flesh of an avocado begins to brown almost immediately after it is exposed to air. If you can't eat the fruit immediately, you should take steps to keep it looking green and fresh.
Lay the avocado halves or slices flat on a cutting board or another even surface.
Sprinkle the flesh of the avocado with either lemon juice, lime juice or white vinegar. The acidic content will help preserve the green color and prevent it from browning. If you want a more full coverage than sprinkling will provide, baste the surface lightly with a basting brush. If your avocados are mashed or pureed, add a few drops of the juice or vinegar and mix it in thoroughly.
Flip the avocado halves or slices over so the untreated side faces up.
Sprinkle or baste the other side with the juice or vinegar.