Gather your ingredients. If you have a kitchen scale, go ahead and weigh the fruit. Make sure you have about 3 pounds of cantaloupe and 1.5 pounds of tomatoes.
Seed and cut the cantaloupe into chunks. My cantaloupe is very large, so I am only using half.
Core, peel and seed the tomatoes. It's important to remove the seeds, as they are impossible to purée. The skins need to be removed since they are bitter.
Cut the tomatoes into chunks.
Heat a couple tablespoons of olive oil in 2 skillets. It's important to use 2 skillets so that the cantaloupe and tomatoes sit in one layer. Turn the heat to high.
Cook the cantaloupe and tomatoes, stirring, for about 2 minutes (or until they become juicy).
Add the cantaloupe, tomatoes, basil leaves, 1.5 cups water, salt and pepper to a food processor or blender. Purée until smooth. If you want to thicken it, and make a bit richer, add more olive oil.
Transfer to a covered container and place in the refrigerator. When chilled, add the juice of one lemon, as well as salt and pepper to taste.
An easy way to swirl olive oil on top of soup is to use a small squirt bottle like this one.
Pour the soup into individual bowls. Swirl some olive oil on top and garnish with a couple basil leaves.