Using a whisk, beat the yogurt by hand until creamy.
Add the lemon zest, lemon juice and sugar and mix well.
Fill about 2/3 of your icecream stand with this mixture and freeze until the raspberry mixture is ready.
In a food processor, grind the raspberries for 5-7 seconds.
Using a sieve, strain the raspberry, to separate the seed
Add 2tbsp sugar to the seedless mixture, and mix well.
Add this mixture on top of the yougurt mixture in your icecream stand, and using a skewer or the back of the spoon, swirl it a bit, to get a gradient effect
Freeze overnight.
Run under water to pull the sticks out.