Remove the meat from the fridge approx. 1 hr. prior to cooking. Preheat the oven to 80°C, warm the platter, plates and sauce boat. Using a mortar and pestle, finely crush the tea, sugar, salt and pepper. Heat the clarified butter in a frying pan. Brown the meat all over for approx. 4 mins., only turning when a crust has formed. Coat all sides of the meat with the tea & spice mix, pressing down firmly. Transfer the meat to the warmed platter. Insert the meat thermometer in the thickest part. Set aside the frying pan.
Cook on a low temperature in the centre of a preheated oven for approx. 2 hrs. Core temperature: approx. 55 °C (à point). Keep warm for approx. 1 hr. at 60°C.
Pour boiling water over the tea, cover and briefly leave to brew, strain into the frying pan. Pour in the wine, add the shallot and cardamom seeds, bring to the boil. Reduce the liquid to 250 ml, strain into a small pan. Using a fork, thoroughly mix the flour and butter. Bring the reduction to the boil, gradually add the flour & butter mixture while stirring, season.
Heat the clarified butter in a frying pan. Stir fry the mange-touts for approx. 3 mins., season.