Increase the heat to high. Add the remaining 2 tablespoons olive oil, bell peppers, and onion to the pan. Season with the remaining 1/4 teaspoon kosher salt and remaining 1 teaspoon taco seasoning. Stir to combine, then cook undisturbed until the peppers and onions and char slightly, 5 to 7 minutes. Stir again and cook until slightly softened, about 5 minutes more. Add the garlic and cook until the garlic is fragrant, about 2 minutes.