Trim all fat from flank steak. Semi-freeze meat, slice 1/8 inch thick. Marinate overnight in refrigerator. Turn occasionally. Drain well on paper towels, pat dry. Lay on an oven rack. Do NOT overlap. Place a cookie sheet on lower oven rack to catch drips. Roast at 125 to 140 degrees for 8 to 10 hours. Leave oven door slightly ajar , taste for chewiness. Store in a brown paper bag. Or use a Dehydrator & follow manufactures instructions.