Halve the lemons, squeeze the juice. Peel the kiwis. Cut 2 kiwis into coarse pieces, put them into a tall mixing bowl and puree finely with a hand blender. Cut the remaining kiwis into thin slices.
Wash the mint, shake dry and pluck the leaves from the stalks.
Put gin, lemon juice, kiwi puree and maple syrup in a shaker, shake well for about 1 minute. Divide kiwi slices and mint into glasses. Top up with the gin-kiwi mix. Add plenty of crushed ice (like an iceberg!).
Top up with mineral water.