Lightly spoon flour into dry measuring cups; level with a knife. Combine 3 cups flour and salt in a small bowl. Add water; stir until soft dough forms. Turn dough out onto a lightly floured surface; knead until smooth and elastic (about 6 minutes); add enough of the remaining flour, 1 tablespoon at a time, to prevent the dough from sticking to hands. Place dough in a large bowl, and cover with a damp towel. Let stand 25 minutes.
Roll the dough into a 20 x 15-inch rectangle. Brush sesame oil over dough, and sprinkle with onions. Roll up dough lengthwise. Cut the dough roll crosswise into 8 pieces. Roll each dough portion, cut side up, into a 6-inch circle on a lightly floured surface.
Heat 1 teaspoon peanut oil in a large nonstick skillet over medium heat. Add 1 pancake; cook 2 minutes on each side. Repeat the procedure with the remaining pancakes.