Avocados -- an essential ingredient in guacamole and other Tex-Mex favorites -- is high in heart-healthy mono- and polyunsaturated fats and other essential nutrients. While avocados can contribute to a healthy diet, storing cut avocados presents a challenge. Slicing avocados disrupts the cell structure of the fruit, exposing them to oxygen. Oxidation turns the cut surfaces brown or black in a couple of hours. Brushing cut avocados with an acidic liquid can keep them attractively green longer.
Cut the avocado lengthwise, using a serrated knife to slice through the tough skin. When the knife edge hits the pit, rotate the avocado until the two halves separate. Gently pull the halves apart.
Remove the pit from the avocado flesh and discard.
Pour about 1 tbsp. of lemon juice into the small bowl. Dip a silicone pastry brush into the lemon juice and then sweep the juice over the entire cut surface of the avocado halves.
Cover the avocado halves tightly with plastic wrap, making sure that the wrap is flush against as much of the avocado flesh as possible.
Refrigerate the avocado halves until you're ready to use them. Cut avocados will stay fresh for only a day or two.