Step 1Cut the cantaloupe in half and discard the seeds. Using a melon baller, make melon balls with most of the flesh. You will have about 4 cups of melon balls. Set these aside to use as a garnish.
Step 2Cut out the rest of the melon flesh and transfer it to a blender. Peel and pit 1 peach. Slice it into chunks and add them to the blender.
Step 3With a sharp knife, split the vanilla bean lengthwise and scrape out the seeds; add them to the mixture in the blender. Add the sugar and lemon juice to the blender. Puree until well blended. Strain the melon mixture through a sieve to remove any small lumps of fruit. You will have about 1 1/2 to 2 cups of soup. (You can make the soup up to a day in advance. Keep it chilled in the refrigerator.)
Step 4Just before serving, peel and pit the remaining 2 peaches. Slice each half into 4 wedges.
Step 5Divide the melon soup among 6 chilled shallow soup bowls. Arrange the reserved melon balls in the middle. Surround the melon balls with the peach wedges. Dot with berries or currants. Garnish with sprigs of mint.
Step 6Serve immediately.