Mix ground turkey, panko, egg, salt, scallions, ginger, soy sauce, and oil and mix with your hands until combined well. Shape 1/4 cup meat mixture into a ball and transfer to a baking dish. Repeat with remaining mixture. Bake until cooked through, about 15 minutes.
For the dipping sauce mix together lime juice, water, soy sauce, and remaining 2 teaspoons of oil in a bowl. Add scallions and sesame seeds.
Transfer meatballs to a serving dish. Stir sauce, then drizzle meatballs with 1 tablespoon sauce.
Serve meatballs with remaining sauce, about 1 tbsp per person. Chances are you won't use all the dipping sauce.