In a food processor, add the Greek yogurt, lime juice and half the zest, olive oil, water, avocado, cilantro, garlic, green onion, and salt. Pulse on high until fully combined. You can add more water if needed to thin out the sauce.
1/2 cup Greek yogurt, 1 lime,, 2 tablespoons extra virgin olive oil, 1/4 cup water,, 1/2 avocado, 3/4 cup fresh cilantro, 1 garlic clove, 1/4 cup green onion,, 1 teaspoon kosher salt