Preheat the oven to 190°C and grease two 20cm sponge tins.
Boil strawberries, jam sugar, and lemon juice for five minutes to create an instant jam.
Cream butter, caster sugar, and salt together until light and fluffy.
Gradually whisk in the duck eggs and fold in the self-raising flour.
Divide the batter between the tins and bake for 25-30 minutes until golden.
Cool the cakes on a wire rack and remove the greaseproof paper.
Caramelize sugar in a pan and dip whole strawberries into it to set.
Layer one sponge with whipped cream and jam, then top with the second sponge.
Dust the cake with icing sugar and garnish with the caramel-coated strawberries.