Mix the flour and salt in a large bowl.
In a separate small bowl combine yeast, warm water, and sugar. Mix well until yeast has dissolved. Let sit for 5 minutes.
Pour the yeast mixture into large bowl of flour, slowly add warm milk to the bowl as well. Mix by hand until a ball is formed.
In a separate bowl lightly dust with flour and set the ball of dough into the bowl. Cover with plastic wrap and cover with a towel. Let it rise in a warm place for 2 hours.
Dust work surface with all-purpose flour. Remove dough from the bowl after 2 hours of rising. Work the dough with your hands stretching into a large square approximately 12 inches by 12 inches, then cut 12 pieces with a bench scraper. Work dough to the desired size and thickness. Transfer to a lightly dusted sheet tray lined with parchment. Let rise again for 15 mins.
Heat grill to medium heat. Place dough on the grill. Use a meat fork to flip flatbread when cooked on one side. When both sides are complete, remove from the grill and place on sheet tray.