Preheat your oven to 400° Fahrenheit and lightly grease a baking sheet lined with aluminum foil.
Heat the olive oil in a large skillet over medium-low heat.
Add the onions and celery, cooking until they soften, which should take about 5 minutes.
In a large bowl, combine the ground turkey, cooked vegetables, dried oregano, Dijon mustard, Worcestershire sauce, salt, and pepper.
Mix everything thoroughly.
Add the egg and breadcrumbs to the mixture in the bowl.
Stir until the ingredients are evenly combined into a loaf shape.
Place your loaf mixture onto the prepared baking sheet.
Shape it carefully and bake in the oven for 45-50 minutes until cooked through.