For flatbread: Add yeast and sugar to the lukewarm water, allow to sit until frothy, about 5 min. In a separate bowl combine flour and salt, fold in the yeast mixture and knead until a smooth dough ball is formed. Cover dough with plastic wrap and place in a warm area for about an hour to rise. Punch down the dough, divide into four pieces and place the pieces on a floured surface. Cover the dough with a damp towel for 30 min. or the dough balls can be refrigerated for later usage.
For topping and assembly: Preheat oven to 450 degrees, place a pizza stone or cookie sheet on the lower rack of the oven. Meanwhile, cook the ground meat in a skillet and drain. Combine the cooked meat with remaining ingredients and set aside. Roll the dough pieces into 10-inch by 6-inch rectangle. Divide the meat mixture between the four flatbreads and spread evenly to the edges. Cook the flatbread until the dough is crisp about 7 min. depending on dough thickness. Flatbreads may need to be baked individually depending on the size of your baking sheet. Cut into strips and, season with salt to taste.