In one bowl, melt butter and add lemon juice. Immerse Tuna steaks in butter/lemon mixture.
Mix almond flour & arrowroot flour in a separate bowl.
Transfer tuna steaks to the almond flour bowl and coat completely with almond flour.
Place on a preheated cast iron skillet set on medium. Cook for about 5-8 minutes on each side, flipping once. On each side, sprinkle salt and pepper to taste.
Recipe by Healthy Witty and Whole at http://healthywittyandwhole.com/2013/03/almond-crusted-tuna-steaks/