Halve the lemon and, in a small bowl, mix with the water.
Wash and peel the oranges, tangerine, banana, pear, and apple (if using the latter). Trim the strawberry tops. Core the pear and the apple, (if using the latter). Trim any pithy parts from the oranges and tangerine as necessary.
Cut the apple and pear fruit into small, bite-sized chunks. Drop the chunks into the lemon water and then pick them back out, allowing any juice to drip off -- place the fruit in a medium mixing bowl.
Cut the banana into small, bite-sized chunks and dip the chunks into the lemon water, allowing the fruit to drain off, through your fingers, before placing it in the bowl with the pear and apple fruit. Discard the lemon water.
Cut the strawberries, the oranges, and the tangerine into small, bite-sized chunks and place directly into the bowl with the other fruit. Make sure to extract any seeds in the oranges and in the tangerine. Toss the fruit carefully.
Cover the bowl and allow the fruit to macerate in the refrigerator for 2-4 hours prior to serving.