Preheat oven to 300° F. Combine spices and spread all over oxtails. Add minced garlic to top of oxtails. Place oxtails in your baking pan or dutch oven.
Place small potatoes and cut up carrots around the oxtails with sliced onions over the top. Add about 2 cups of water or broth to cover the bottom of the pan and about 1" deep to create steam.
Cover the pot with a lid. Bake for about 3 hours or until meat inside bones is tender with a fork. Timing will vary depending on how large yours are.