How to Make It
Preheat oven to 350°F. Line a 9- x 5-inch loaf pan with parchment paper. Add tea bags to 1 1/4 cups boiling water, and let steep 10 minutes. Discard tea bags. Add prunes; let stand until some tea is absorbed and prunes are softened, about 10 minutes.
Whisk together eggs in a large bowl until thoroughly blended; slowly stir in tea and soaked prunes. Stir in brown sugar and orange zest until just combined.
Add flour, baking powder, and fine sea salt to tea mixture. Using a rubber spatula, gently fold until no streaks of dry flour remain.
Pour batter into prepared loaf pan, and bake in preheated oven until a wooden skewer inserted in center comes out clean, 1 hour to 1 hour and 10 minutes. Let cool in pan on a wire rack 10 minutes. Remove from pan, and let cool completely on wire rack, about 1 hour and 30 minutes.
Cut loaf into thin slices, and lightly toast in a toaster or dry skillet. Spread generously with butter, and sprinkle with flaky sea salt.