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 approximately 1 heaping tablespoon per ball. Place shaped balls on a tray.
03 - Heat olive oil in a large nonstick skillet over medium heat. Fry salmon balls in batches, turning occasionally, until golden brown and cooked through, approximately 8–10 minutes total. Transfer to paper towel-lined plate.
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 salmon balls warm, drizzled with creamy avocado sauce or arranged with sauce on the side for dipping.