In a bowl, combine strawberries with lemon juice and sugar. Let them sit for 10 minutes to release juices.
Prepare all fruits and set them in separate bowls.
In a large trifle dish, start with a layer of cake cubes at the bottom.
Add a layer of vanilla custard, spreading it evenly.
Add a mixture of fruits: strawberries, blueberries, mango, and kiwi.
Add a layer of whipped cream over the fruits.
Repeat layers: cake, custard, mixed fruits, and whipped cream until all ingredients are used.
Finish with a generous layer of whipped cream on top.
Decorate with extra fruit and fresh mint leaves.
Chill the trifle for at least 2 hours before serving to allow flavors to blend.