Preheat oven to 350 degrees; butter an 20 cm square baking pan. In a 1-cup glass measuring cup, pour the boiling water over 2 teaspoons of the tea; let steep for 5 minutes, then strain through a very fine strainer. In a small heavy saucepan over low heat, melt the unsweetened chocolate with the butter; set aside to cool for 10 minutes. In a small bowl with an electric mixer on high speed, beat the eggs until they are well beaten, then gradually beat in the sugar; continue beating until the mixture thickens slightly. Reduce the mixer speed to low; beat in the chocolate mixture, 2 tablespoons of the strained tea, and 1 tablespoon of the creme de cassis. Fold in the flour mixed with the salt, just until blended. Pour the batter into the prepared pan; bake for 25 to 30 minutes, or until the brownies are shiny and firm on top and begin to shrink from the sides of the pan. Cool for 10 minutes on a cake rack. Combine remaining 2 tablespoons creme de cassis and 1 tablespoon of the strained tea; brush over the top of the brownies. Cool completely. In a small saucepan over moderate heat, melt the preserves, stirring often to prevent burning. Strain and brush over the top of the brownies. In a small heavy saucepan over moderately high heat, bring the cream to a boil; remove from heat and stir in the remaining 2 teaspoons of the tea. Let steep for 5 minutes; strain through a very fine strainer and return to the saucepan. Return to a boil, then pour over the chopped chocolate in a small bowl; let stand for 1 minute, then beat with a wire whisk until smooth. Spread the ganache in an even layer over the preserves. Refrigerate until the ganache is partially set, then score the top into bars. Store in the refrigerator, lightly covered with plastic wrap. Serve at room temperature. Note: Other fruit-flavored teas, liqueurs and preserves, such as raspberry and apricot, may be substituted for the black currant tea, creme de cassis and preserves.