Start by bringing the water, sugar, strawberries, and sage up to a simmer for 5 minutes.
Remove from heat, cover, and steep until totally cooled. Strain and pour into a pint jar with a lid. Chill until you're ready to make your latté.
Fill a quart jar with ice. Pour 2 tablespoons of strawberry sage syrup into your jar. Add in 1 cup of chilled green tea. Pour in your oat milk. Stir to combine.