Brown the ground beef, onion, garlic, taco seasoning and oregano in a frying pan over medium heat, breaking the meat up into crumbles as it cooks (about 8 minutes). Drain off excess fat. Stir in sour cream, chillies and vinegar until well mixed. Remove from heat and mix in the cheddar cheese.
Melt margarine in a small frying pan over low heat. When melted, dip each tortilla into the margarine for about 30 seconds. Place the tortilla onto a baking tray and fill with about 1/3 cup of the meat mixture. Fold the right and left sides of the tortilla over the filling then the top and bottom, making an envelope that completely encloses the filling. Flip the tortilla seam side down on the baking tray. Repeat with remaining tortillas and filling.
Bake in the preheated oven until the tortilla is crisp about 15 minutes.