Heat a non-stick sauté pan over medium-high heat. Add one tablespoon of butter and heat until melted.
Add the chopped onion and cook for a few minutes, until starting to soften.
Add the ground sirloin and cook until the meat is no longer pink, breaking up the meat with a spoon or spatula as it cooks.
Add the garlic and cook, stirring until fragrant, about one minute.
Stir in the taco seasoning and salsa and cook for about one minute more.
Add the beef mixture to the insert of your slow cooker.
Then add the beans, corn, tomatoes, consommé and chicken stock. Stir well and put the lid on the slow cooker.
Cook the soup on high power for 4 hours or on low for 6 hours.
Stir in 2 tablespoons of fresh lime juice when ready to serve.
Serve the soup topped with tortilla chips, avocado, shredded cheese and sour cream.