In a food processor, purée half of each of the raspberries, strawberries and mange tout thouroughly. Transfer to a sieve with a bowl underneath it. Press the pulp down with the back of a spoon, occasionally, whilst you leave it to stand and drain until needed.
Halve the remaining strawberries, then along with the remaining raspberries, mange tout and mint, place them in a large serving jug and squash them down with the end of a rolling pin.
Add the sugar, rum and juice, discarding the pulp and mix thoroughly. Fill with ice, then pour in the soda water to the top.
*All information included in this recipe has been provided by Angus Soft Fruits.