01 - In a large bowl, combine chopped salmon, onion, garlic, dill, parsley, egg, breadcrumbs, Dijon mustard, lemon zest, salt, and pepper. Mix until just combined; do not overwork the mixture.
02 - With damp hands, shape the mixture into small balls using about 1 heaping tablespoon per ball. Place on a tray and set aside.
03 - Heat olive oil in a large nonstick skillet over medium heat. Fry the salmon balls in batches, turning occasionally, until golden brown and cooked through, about 8–10 minutes total. Transfer to a plate lined with paper towel to drain excess oil.
04 - Blend avocado, Greek yogurt, lemon juice, olive oil, garlic, cilantro or parsley, salt, and pepper in a food processor or blender until smooth and creamy.
05 - Serve the salmon balls warm, drizzled with the creamy avocado sauce or arranged on a platter with the sauce on the side for dipping.