Place the pear, plum, lemon, and fresh ginger in a bowl. In a non-reactive saucepan, combine the water, sugar, and rice wine vinegar. Bring the liquid to a simmer and cook until sugar dissolves.
Place the fruit mixture into a spring-top glass jar and add the sprig of mint to the fruit. Slowly pour the hot pickling liquid over the fruit, filling the jar to the top.
Cool the pickles, then refrigerate for 2 days up to 1 week before serving.