Dice: Cut the apple into quarters and remove the core. Slice each quarter through the thick edge. Then, cut the slices into strips and finally into dice. Remove the tops of the strawberries and the pit of the peaches. Cut them into small dice.
Wedges: Slice off the top and bottom of the orange. Stand them on one of the flat edges and run a paring knife along the peel. Hold the orange/grapefruit in your hand and make cuts along the white membranes to release the segments. Cut the segments into 3 or 4 pieces. Squeeze the rest of the orange and grapefruit into a large bowl and use the juice as a dressing for the fruit salad.
Mint: Separate the leaves from the stems. Chop them as finely as possible.
Combine: Add the strawberries, peaches, kiwi, apple, grapefruit, oranges, and mint to the bowl with the orange and grapefruit juice. Gently toss to combine.