Piping-hot lemonade makes a surprisingly satisfying autumn drink. If you're packing this lemonade for a picnic, pour it into a large thermos while it's still hot.
Place sugar and mint in a large bowl. Using a wooden spoon, press the mint and sugar against the side of the bowl until the sugar resembles wet sand and the mint is bruised. Stir in 2 quarts water.
Transfer mixture to a pot; heat over high heat until almost at a boil. Turn off heat; stir in lemon juice. Pass through a sieve; discard mint. Serve hot, garnished with a sprig of mint if desired.