In a saucepan, boil ½ cup (100 g) sugar, water, and acai puree.
2. Step
Reduce heat to simmer and cook until mixture thickens into a syrup. Add lemon when thickening.
3. Step
Let cool before using.
4. Step
Preheat oven to 225˚F (105˚C). Line a baking sheet with parchment paper and set aside.
5. Step
In a bowl, using an electric mixer, beat the egg whites until they are foamy.
6. Step
Add salt and lemon juice. Continue whisking.
7. Step
Slowly add sugar while whisking and beat until glossy, stiff peaks form.
8. Step
Spoon meringue mixture on the parchment sheet and smooth the top of the meringue with the back of the spoon.
9. Step
Drizzle about ¼ teaspoon of acai syrup on the meringue and swirl with a toothpick. Repeat for each cookie.
10. Step
Bake for 90 minutes, until the outside shell becomes stiff and the meringue has gone from shiny to matte. The cookie should easily lift off the parchment.