In a large pot over low heat, bring milk to a simmer. Add lavender sprigs and lemon zest. Cover and let infuse for 10-15 mins.
In the meantime, in a large heatproof bowl, combine sugar and tapioca starch until well incorporated.
Strain the milk mixture through a fine mesh sieve directly over the sugar and tapioca mixture. Press the lavenders to extract as much flavor as possible.
Discard lavender sprigs and zest.
Stir the mixture until combined. Microwave the pudding for 1:30 mins, stir. Repeat until you get the right texture (about 4 to 5 times, depending on your microwave)
If you do not want to use the microwave, simply pour the mixture back in the pot, over low to medium heat, stirring constantly until it thickens.
Pour in tea cups, cover immediately with cling film and refrigerate for 2 hours or until ready to serve.
Decorate with lavender sprigs and place tea cups on their matching plates.