Drizzle, spoon, or dollop this tangy, creamy sauce on everything: rice and beans, salmon, chicken, quesadillas, tacos, eggs . . .
Use butter knife to cut avocado in half lengthwise around pit. With your hands, twist both halves in opposite directions to separate. Use soupspoon to remove pit. Scoop avocado from skin into food processor; discard pit and skin.
Add water, cilantro, lime juice, sour cream, and ¼ teaspoon salt to food processor and lock lid into place. Process mixture until completely smooth, about 1 minute. Stop food processor. Carefully remove food processor blade (ask an adult for help). Use rubber spatula to transfer avocado crema to small bowl. Serve.