I actually had lunch at Tortuga Tavern at MK last week! It's right across from Pirates, and they have indoor and outdoor seating. The menu is a little bit limited, but they do have a taco salad. They give you the taco salad shell, filled with taco meat. After getting it, you head over to the fixin' bar, where you fix you own food. They have lettuce, cheese, salsa, etc. I love it because you can load it up with as little/as much of the ingredients that you want. If your kids don't like the chunky salsa that is on the bar, there is also a basket of "regular" taco sauce in the packs (taco bell style) on the end of the bar as well.
In the past few trips, I've always found this place to be open, but only at lunch. It was open from 11-3 on my last two visits. The listed price for the taco salad is $8.19...I found it pretty yummy.
Happy dining