Place the lima beans in a microwave-safe bowl, cover them with water, and add a pinch of salt.
Microwave on High for 2 minutes (or bring to a boil in a saucepan over high heat and cook for 5 minutes) until partially cooked.
Drain, reserving ¼ cup of the cooking liquid (add water if necessary).
Soak the bread slices in water and then squeeze them dry.
In a food processor, combine the soaked bread, garlic cloves, partially cooked lima beans, salt, and wine vinegar.
Process until smooth.
With the food processor running, gradually drizzle in the olive oil until fully incorporated, creating a mayonnaise-like consistency.
Transfer the mixture to a medium bowl and stir in the reserved ¼ cup of cooking liquid and the chicken or vegetable broth.
Taste for vinegar and salt and adjust if necessary.
Cover the bowl and refrigerate the gazpacho for at least 2 hours, or overnight, to chill and allow the flavors to meld.
Before serving, taste the gazpacho and adjust the seasoning if needed.
Pour the chilled gazpacho into individual bowls and float the small cubes or balls of melon in the soup.
Serve the gazpacho cold.