Place the thawed boneless turkey breast into a 9 x 13" baking dish, fat or skin side up. Pat it dry using paper towels. Sprinkle with sea salt on all sides.
In a small bowl, combine the room-temperature butter, garlic, thyme, rosemary, sage, onion powder, and pepper, then use a fork to mash and combine all of the ingredients.
Arrange the carrots and onions around the edge of the turkey breast, then stick a meat thermometer into the thickest part of the turkey breast and place it uncovered in the preheated oven.