For Rooibos Tea Syrup: Pour boiling water over tea bags and let steep 5 minutes. Remove tea bags. Stir in sugar to dissolve. Let cool before using. Syrup can be stored in refrigerator for up to 1 week.
In a mixing glass, muddle peach slices, rooibos syrup, and lemon juice into a rough pulp. Add cognac and Lillet blanc, stir to mix. Pour unstrained into serving glass.
Fill serving glass with crushed ice, garnish with large bunch of mint.