Place mint leaves and 10 tea bags in a big pitcher. Pour boiling hot water over the mint and tea, let steep for 30 minutes or longer; let cool. To serve, fill tall glass with ice and fill with 1/3 tea mixture, 1/3 water and 1/3 sparkling water on the top. (Similar to Starbucks, I brew smaller batches of strong tea then add water to serve.) Serve with fresh lemon and extra mint sprigs.