Cut melon in half and scrape out seeds with a spoon. Scoop the flesh with a melon baller.
Rinse strawberries, trim and pat dry.
Put melon balls along with the strawberries in a bowl. Stir lemon juice with powdered sugar (to taste) and pour over, gently combine and chill for about 2 hours in the refrigerator.
To serve dish into nicely rinsed and trimmed melon halves, top with a scoop of vanilla ice cream and a dollop of strawberry jam, garnish with mint leaves.