Pat Dry the turkey breast, set aside.
Mix onion powder, garlic powder, smoked paprika, dried tarragon, cumin, fresh thyme and turmeric in a bowl. Then add in olive oil and mix so it forms a paste.
Rub the paste all over the turkey breast and under the skin.
Place garlic, onions, carrots and celery at the bottom of the slow cooker, place the turkey on the vegetables. Cover and cook on low for 6-7 hours until the internal temperature registers at 165F.
Let the turkey sit for 20 minutes and then slice and serve.