Freeze bowl of ice cream maker overnight before use.
In a small pot, boil water over high heat. Add tea bags and steep for 5 minutes. Remove bags from pot and discard. Add remaining ingredients and stir to combine.
Remove from heat and transfer to a large bowl to cool to room temperature. Cover and place in refrigerator until chilled, about 1 hour.
Remove ice cream bowl from freezer and secure in ice cream maker. Pour chocolate hazelnut mixture into bowl and start ice cream maker.
Sorbet is finished when frozen.
Serve garnished with fresh raspberries.