Add the cooled roasted strawberries and their juices to a shaker and muddle well.
Add lime juice, orange juice, 5ml agave and salt. Fill with ice and shake vigorously. Double strain over fresh ice.
Top with 40–60ml soda water — just enough to lengthen it without turning it into a fizzy strawberry drink. Taste and add additional agave only if your strawberries need it.