Heat grill. In medium bowl, combine ground beef, bread crumbs, taco seasoning mix and milk; mix well. Shape mixture into four 4-inch patties. In medium bowl, combine frozen potatoes and soup; blend well.
Cut four 18x12 inch pieces of heavy-duty foil. Place 1 patty on each; top with 1/4 of potato mixture. Wrap each packet securely using double-gold seals, allowing room for heat expansion.
When ready to grill, place packets, seam side up, on gas grill over medium heat, on charcoal grill 4 to 6 inches from medium coals, or on campfire grill over medium heat. Cook 30 to 40 minutes or until burgers are no longer pink in center, rearranging packets several times during cooking.
To judge the temperature of a fire, cautiously hold you hand, palm side down, over the fire at cooking height. Now, count the number of seconds you can hold that position and you will have an indicator of how hot the fire temperature is: