Lightly grease a large skillet; set aside. In a large mixing bowl, stir together the flour and cornmeal. Stir in water to form a crumbly dough. Work dough with hands until it holds together. On a floured surface, knead dough until smooth. Divide dough into 10 to 12 pieces. (For large tortillas that are burrito size, divide into 5 or 6 pieces.) Roll each into the shape of a ball. Cover lightly with plastic wrap and let dough rest for 10 to 15 minutes. Flatten each piece of dough by hand, then roll into a 8 to 9-inch round tortilla. Place one tortilla in the pan and heat over medium heat. Cook tortilla until light brown, turning to ensure equal browning. Repeat with remaining tortillas. Makes 6 to 12 tortillas, depending upon size made.