In a skillet, melt bacon grease over medium heat. Saute meat, onion, garlic, tomatoes, chilies and potato until the onion softens. Add salt, oregano, chili powder and cilantro; simmer 2-3 minutes. Place a scant 1/2 cup meat filling on each tortilla. Fold, envelope-style, like a burrito. Fry, seam side down, in 1/2 in. of hot oil. (360°-375°) until crispy and brown. Turn and brown other side. Drain briefly on a paper towel. Top as desired; serve immediately.