Preheat oven to 425°F Spray large baking sheet lightly with non-stick cooking spray. Sift flour, baking powder and salt into food processor bowl. Add sugar. Pulse just enough to blend dry ingredients. Add butter and pulse until largest pieces are the size of fat peas.
In a small bowl, lightly beat together eggs, tea and the 1/4 cup of milk. Add all at once to flour and butter mixture. Pulse a few times to distribute the wet mixture. Add the remaining milk a spoonful at a time and pulse just until dough comes together in a soft but not sticky ball.
Turn dough out onto a lightly floured surface. Add a little extra flour if the dough seems sticky and difficult to handle. Sprinkle cranberries and lemon zest on dough and gently knead into a rough ball. Roll and pat into a long log shape. Then bring ends together into a ring. Place on baking sheet and cover with plastic wrap and chill 10 minutes to allow gluten in the dough to relax.
Place baking sheet in center of oven and bake for 25 minutes. Meanwhile, lightly beat glaze ingredients. Remove cake from oven and brush all over with glaze. Return cake to oven for an additional 15 minutes, or until it turns a rich golden brown. Transfer the cake to a wire rack to cool. Stir together icing ingredients until smooth and runny. Dribble over just warm cake, allowing it to drip down sides. Best eaten as soon as possible.