In a pan, cook ground beef and onion until browned. Drain. Add 1 package of taco seasoning mix.
In another pan, combine 1 package taco seasoning mix, refried beans, worcestershire sauce and 3 tablespoons cheese and heat until cheese is melted and beans are hot.
Heat oil in a pan large enough to hold tortillas. When oil is hot, fry tortillas until golden brown on each side. Drain on paper towels.
To service, spread each tortilla with bean mixture, top with seasoned meat, lettuce, diced tomatoes and remaining shredded cheese. Serve with salsa or taco sauce.