Traditionally made in Finland to celebrate the arrival of spring, this fermented lemonade couldn’t be simpler and is a great introduction to fermentation. The yeast kick-starts the process, feeding off the sugar to begin breaking down the cells of the lemon and eventually naturally carbonating the drink. The longer this lemonade ferments, the more likely it is to become alcoholic, so if you want to avoid this then consume as quickly as possible after the bottles have been refrigerated, which will slow down the fermentation. It’s important to remember that heat will speed up the fermentation process, so if you leave the bottles in a hot room or live in a warmer climate you may need to refrigerate the bottles sooner than stated to avoid over-carbonation, which will cause the bottles to explode. To do this, keep an eye on the raisins at the bottom of the bottles – when they are all floating, your Sima will be carbonated and ready for refrigeration. When you zest the lemons, make sure to discard the white rind as it adds bitterness. Once zested, cut the flesh of the Lemon into thin slices and add to the container as well. This recipe makes enough Lemonade to fill 5 x 500 ml bottles. Make sure your bottles are sterilised by running through a dishwasher or rinsing with boiling water and drying in a very low oven, and always leave a gap of around 3cm of air at the top of your bottles when filling.