I would stay far away from fast food during Phase 1. There are traces of sugar in everything, including grilled chicken, and they could screw up your detox.
There is probably sugar in the salsa, way too much bad fat in the beans, bad fat in the cheese and sour cream, and both sugar and bad carbs in the meat, not to mention even more fat. I'd stay away from that monster.
You can make a great taco salad at home, just use lean ground beef, your own seasonings (watch for sugar), vegetarian or fat free beans, (or canned, but watch for sugar!), and make your own salsa or find one without sugar. Then use red. fat cheese and sour cream, and add broccoli and cabbage, etc. to beef up the veggie content.

I also love Fantastic Foods' soy Taco Filling. It's awesome, but it does have a little wheat so I wouldn't eat it during Phase 1.
Hope this helps!