In a large skillet cook mushrooms and onion in 1 tablespoon of the oil over medium-high heat for 5 minutes or until mushrooms are tender and starting to brown, stirring once. Remove and set aside to cool slightly.
In a large bowl beat egg with a fork. Stir in bread crumbs, turkey, garlic powder, and salt until combined. Stir in mushroom mixture. Using an ice cream or cookie scoop, shape mixture into 12 to 15 balls.
Heat remaining 1 tablespoon oil in the same skillet over medium heat. Add meatballs. Cook for 10 minutes or until cooked through (165°F), turning occasionally to brown evenly.