In a medium bowl place cut fruit, blueberries, lemon juice and 1 tablespoon sugar. Mix well and macerate for about 10 to 15 minutes. This will allow fruit to be infused with lemon juice and sugar. Meanwhile in a small bowl stir 450g of low-fat yoghurt and poppy seeds. In clear glasses, layer the ingredients starting with the fruit mixture then next layer with yoghurt, then fruit, then yoghurt. Repeat these steps until you have filled the glasses. Garnish with a sprig of mint.