Combine orange
juice, lemon juice, sugar, orange rind, lemon rind and salt in a small
saucepan. Bring to a boil, turn down heat, simmer 5 minutes. Pour into a
shallow metal pan and cool. Put in freezer and chill until a few ice
crystals form around the edges. Peel and slice peaches. Peel and cube
pears. Mix these fruits with the blueberries and spoon some of the mixture
into each of 6 sherbet glasses. Spoon a little of the icy orange juice
mixture over each. Garnish with sprigs of mint and serve immediately.