1 lemon, washed and sliced crosswise (an orange may be substituted for the lemon)
A 2-liter bottle of lemon-lime soda, use half for ice ring and reserve remainder for punch
1 large watermelon, chilled
1 6-ounce can frozen orange juice concentrate
¾ cup sugar or to taste
Slice the lemon and arrange in a circular ring mold pan. Fill with one liter of the lemon-lime soda. Freeze.
Cut watermelon into halves. Scoop out pulp and place in blender, seeds and all.
Blend for several seconds on medium speed. Strain through fine sieve colander, squeezing out juice.
Place watermelon juice in large container with lid. Add orange juice concentrate and sugar and stir until sugar and orange juice are dissolved. Chill until ready to serve.
When ready to serve, pour watermelon mixture into a clear glass or plastic punch bowl. Add the remaining liter of lemon-lime soda and stir. Place ice ring in the punch bowl and serve.