Cut roast into quarters; rub with dry soup mix. Place roast in a large crockpot. Dissolve soup base in water; pour around roast. Sprinkle roast with garlic. Cook on high until beef is tender enough to pull apart with 2 large meat forks (about 5 hrs.). Remove meat from juices, pressing as much liquid as possible out of the meat; shred beef. Add tomato sauce to beef juice, stirring to combine; keep warm. Place about 2 tbsp. of shredded beef in center of each tortilla; fold in half. Fry each tortilla in hot oil on each side until crisp (about 2 min. per side); drain. Keep warm until ready to serve.
To Serve: Arrange 2 tacos on a dinner plate; top with shredded lettuce, cucumbers, carrots, onion, Salsa Fresca, warm beef juice and cheese.