In a large bowl, mix breadcrumbs and milk until soaked and spongy
Add egg, grated onion, garlic, parsley, salt, pepper, paprika, and oregano
Mix gently until just combined
Add ground chicken and gently mix until incorporated
If mixture feels too wet, add 1–2 tablespoons breadcrumbs
Lightly oil hands and shape into golf-ball-sized meatballs
To Pan-Fry
Heat olive oil in a skillet over medium heat
Add meatballs in a single layer
Cook 8–10 minutes, turning gently, until golden and cooked through (165°F)
To Bake
Preheat oven to 400°F (200°C)
Place meatballs on a parchment-lined baking sheet
Bake 18–20 minutes, flipping halfway
To Air Fry
Preheat air fryer to 380°F (193°C)
Arrange meatballs in a single layer
Cook 10–12 minutes, shaking halfway