Place the rooibos leaves in a large teapot or other heat-safe pitcher and pour the boiling water on top. Cover and steep 5 minutes, then strain out the rooibos and stir in the honey. Allow to cool to room temperature.
Combine the tea with the peaches and lemon juice in a blender and puree until smooth. Strain out the pulp and gently stir in the sparkling water.
Put a scoop of ice cream into each of four glasses, then top with the peach tea.