Begin by washing the ripe yellow peaches thoroughly to remove any dirt. Next, cut the peaches in half, remove the pits, and slice them into eighths, discarding any imperfections.

In a blender, combine the sliced peaches and caster sugar. Blend on high speed until you achieve a smooth, creamy consistency, which should take about 1-2 minutes.

Once your peach and sugar mixture is smooth, gradually add lemon juice while blending. Blend for an additional 30 seconds until fully combined.

Pour the blended peach mixture into an airtight container, spreading it evenly. Place the container in the freezer and allow it to freeze for 6-7 hours, or until firm.

Before serving, remove the peach sorbet from the freezer and let it sit for about 5-10 minutes to soften slightly. Use a sturdy ice cream scoop to portion the sorbet into chilled bowls or glasses.