Combine sugar and water in a small saucepan; bring to a boil and boil for 5 minutes. Remove from heat, cool slightly. Reserve one lemon to slice for garnish. Grate zest of two lemons; juice eight lemons. Combine juice and zest with warm syrup. Steep one hour. Strain. To serve: Mix 1 part lemonade concentrate with 2 parts water. Serve over ice. Garnish with lemon slices and mint.