In a large skillet over medium heat, add the ground beef. Use a spatula to break it up as it cooks. Brown the beef for about 5-7 minutes until it is no longer pink.
Once the beef is browned, add the chopped onion and minced garlic to the skillet. Stir frequently for another 3-4 minutes until the onion becomes translucent and fragrant.
Sprinkle in the taco seasoning mix and pour in the tomato puree. Mix well to combine all the flavors. Allow the mixture to simmer for about 5 minutes, stirring occasionally.
While the beef is simmering, chop your lettuce, red cabbage, and cilantro. If using, grill the sweet corn and cut the kernels off the cob.
Heat the tortillas in a dry skillet over medium heat for about 30 seconds on each side, or until warm and pliable.
To assemble, take a warm tortilla and add a generous scoop of the seasoned ground beef mixture. Top with lettuce, red cabbage, cilantro, grilled corn, guacamole, and a sprinkle of cheddar cheese. Squeeze fresh lime juice over the top to enhance the flavors.