The first thing you need to do is cook your sirloin and drain it. Set aside.

Throw your butter into a large pan over medium heat. Now take your cut up cabbage and shredded carrots and put in sizzling pan. Personally I like using a wok when I work with cabbage because prior to being cooked down, its a pretty large veggie and takes a lot of space.  Saute your veggies for about 5 minutes, rotating often until they are crisp tender.

Dump your drained meat and (non drained) tomatoes into a slow cooker or large soup pot. Add your cabbage, carrots, beef broth, garlic, seasonings and stir.

Now add your taco seasoning and stir. Leave on low in a slow cooker for 2 hours or until veggies are soft, then move to warm.

If you cook in a stock pot, keep on low heat for approximately an hour, stirring frequently, until veggies are tender. I do not like to monitor a pot on a stove, so I always find it best to throw in a slow cooker. If you need it to be done quicker, you can move your soup to high heat for an hour and then back down to low or warm.