To prevent sliced fruits like apples and pears from oxidizing and turning brown before serving, start by juicing one lemon.
Roll the lemon on the counter to release the juice. Then slice it in half and juice it through a strainer or sieve into a bowl of ice water. Use the strainer so that seeds don't fall through.
Then slice the fruit into the desired size and shape, and place in the lemon water.
Store the fruit in the refrigerator as needed until ready to serve or eat. The young presenter discusses the technique as a solution for taking fruit for a meal when using a bento box carrier.