Add celery, carrots, onion, and garlic to the slow cooker.
Stir in cream of mushroom soup, gravy mix, and all seasonings.
Pour in chicken broth and mix well.
Place smoked turkey leg on top.
Cover and cook on low for 8 hours (or high for 6–7 hours).
Remove turkey leg, discard skin and tendons, and shred meat.
Return shredded turkey to the slow cooker.
Stir in both packages of Knorr rice.
Cover and cook on high for 30 minutes, until rice is tender.
Add about 3 cups water or broth to reach desired consistency.
Stir, taste, adjust seasoning if needed, and serve.