1. Put tea in teapot and pour in 1 cup boiling water, then swirl gently to warm pot and rinse tea. Strain out and discard water, reserving tea leaves in pot.
2. Add remaining 4 cups boiling water to tea and let steep 2 minutes. Stir in the sugar to taste and the mint sprigs. Steep 3 to 4 minutes more. Serve in small heatproof glasses.