These grown-up versions of gumdropsare tart and chewy citrus cubes.
In a small bowl, combine gelatin and 1/4 cup cold water; let soften 5 minutes.
In a medium saucepan over medium heat, stir sugar into 1/2 cup water until it dissolves. Without stirring, cook until mixture reaches 255 degrees on a candy thermometer; wash down sides of pan with a wet pastry brush to prevent crystals from forming. Remove from heat.
Whisk gelatin mixture and lemon juice into syrup in saucepan. Pour the mixture into an 8-inch square baking pan. Cover with plastic wrap; let stand until firm, at least 4 hours or overnight.
Invert pan onto a clean cutting board. Using a hot, wet knife, cut into squares. Dip gently in sugar, turning to coat.