To make caramel sauce, in 1-quart saucepan, mix sugar, 1/3 cup water and the lemon juice. Heat over medium-high heat until bubbles form and mixture is simmering. DO NOT STIR but occasionally lift saucepan from heat and very gently swirl mixture while sugar is heating. In about 10 minutes, sugar will start to caramelize; resist the urge to stir. Simmer until mixture is a rich, dark amber color. Remove from heat.