Use equal parts sugar, water, and fresh basil leaves (pack the basil leaves tightly). Heat in a saucepan until the sugar dissolves, then leave it to steep for 30 minutes before straining the basil. Once cooled, store it in a jar in the refrigerator for 3-4 weeks – ready for multiple batches of basil lemonade (+ mocktails, vegan sorbet, and desserts). The general ratio is 4:1:1 water, lemon juice, and basil syrup, but you can adjust that.