Step 1

Purée cucumbers, garlic, and ½ cup water in a blender until smooth. Add arugula, herbs, vinegar, and a large pinch of salt and purée, stopping to scrape down the sides of the blender as needed, until very smooth. With the motor running, slowly stream in oil; blend until emulsified. (The mixture will turn pale green and look creamy, almost like a salad dressing; add more oil and/or water if needed.) Taste gazpacho and season with more salt and vinegar as desired—you want it to be borderline too salty and acidic at room temperature. Transfer gazpacho to an airtight container; cover and chill until very cold, 4–12 hours.

Step 2

Taste gazpacho and adjust with a little more salt and/or vinegar as needed just before pouring into chilled glasses.