Preheat your oven to 400°F (200°C).
In a large skillet, heat the olive oil over medium heat. Add the chopped onion and minced garlic. Sauté for 2-3 minutes until fragrant and the onion is translucent.
Add the ground turkey to the skillet. Cook for 5-7 minutes, breaking it apart until browned and fully cooked.
Stir in the diced bell pepper and taco seasoning. Mix well, then pour in the tomato sauce and let it simmer for another 2-3 minutes.
Assemble the tacos by placing a generous amount of turkey filling into each taco shell and topping with shredded cheese.
Arrange the filled taco shells in a baking dish and bake for 10-12 minutes until golden brown and crispy.
Remove from the oven and let cool for a minute before serving.