Stir tea and water in a small bowl; let steep for 5 minutes. Strain into a medium saucepan; stir in brown sugar. Bring to a boil over high heat; boil until slightly thickened, about 2 minutes. Place prunes in a large bowl; stir in hot syrup. Set aside to cool to room temperature, about 1 hour.Advertisement
Meanwhile, sterilize two 1-pint canning jars by steaming them upside down, their lids alongside, in a closed steamer for 10 minutes; or place in a large pot and cover by 1 inch of water and boil for 10 minutes.
Drain prunes, reserving liquid separately. Whisk Armagnac (or cognac) into the liquid. Pack each sterilized jar with half the prunes. Nestle half the vanilla bean in each jar. Pour 1/2 cup of the Armagnac mixture into each jar. Seal and turn upside down to blend ingredients. Set right side up and store in the refrigerator for 1 week to plump.
Tip Refrigerate the prunes in sealed jars for up to 2 months. When giving, include a card with serving suggestions: “Spoon these ‘drunken prunes' over vanilla frozen yogurt, mascarpone cheese or plain yogurt.”