Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, sesame seeds, salt, and baking powder in a food processor; pulse just until combined. Add oil, and pulse until combined. Add onions; pulse until combined. Add water; pulse until mixture begins to hold together (do not allow dough to form a ball).
Place dough on a lightly floured surface. Divide into 12 equal portions, shaping each portion into a ball. Working with 1 portion of dough at a time (cover remaining portions to prevent drying), roll each portion into a 5-inch circle between 2 sheets of heavy-duty plastic wrap. Stack pancakes between single layers of wax paper or paper towels to prevent sticking.
Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Place 1 pancake in pan, and cook for 20 seconds or until lightly browned. Turn and cook 20 seconds or until lightly browned. Remove from pan, and keep warm. Repeat the procedure with cooking spray and remaining pancakes. Cut each pancake into 6 wedges. Serve warm.