Preheat the oven to 350F. Line a baking tray with aluminium foil and grease it lightly.
Add the ingredients for the spice rub to a mortar and grind them all using a pestle to a fine powder.
Place the tuna steaks in a glass or non reactive bowl. Add the spice mix, olive oil, crushed garlic, lime juice and mix well using your hands or alternatively, you can add all the ingredients to a ziploc bag and mix well.
Cover the bowl with a lid or plastic wrap and marinate the fish for 2 hours. Place the marinated fish on the baking tray, and bake for 14-15 minutes or until you can easily flake the fish using a fork.
Enjoy the baked tuna steaks with spice rub while it is warm.
