Soak bread in a bowl with about 1/2 cup cold water for one minute. Squeeze bread tightly to remove excess water and place wet bread (it will look like a piece of dough) in a blender. Discard soaking liquid.

Add watermelon, garlic, chile (if using), vinegar, salt, and sugar into the blender with the bread. Puree until smooth.

Drizzle oil into the watermelon mix and blend again until completely liquefied. You can work in two batches if the mix doesn’t fit at once in the blender.

Pour soup into a large glass bowl or pitcher.

With a rolling pin or the back of a saucepan, pound the ginger and lemongrass to release their flavors, but DO NOT break them into pieces.

Place pounded ginger and lemongrass into the container with the soup. Cover and refrigerate overnight, to let all the flavors develop.

Before serving, force soup through a sieve into a bowl or pitcher, pressing firmly on solids. Discard solids.

Check for seasoning. If it needs them, add more salt and/or vinegar and serve in individual soup bowls.

Top with cilantro leaves and a drizzle of olive oil.

Serve soup chilled. Soup can be kept covered in refrigerator for two days.