Heat vegetable oil in a 10-inch nonstick skillet over moderately high heat until hot but not smoking, then arrange 7 dumplings, seam sides up, in a tight spiral pattern in center of skillet. Arrange remaining 17 dumplings along outer edge (they should touch one another). Fry dumplings until bottoms are pale golden, 2 to 3 minutes. Add 1/2 cup water, tilting skillet to distribute, then cover tightly with a lid and cook until liquid is evaporated and bottoms of dumplings are crisp and golden, 7 to 10 minutes. (Use a spatula to loosen and lift edges to check bottoms; replace lid and continue cooking if necessary, checking after 1 to 2 minutes.) Remove lid and invert a large plate with a rim over skillet. Using pot holders and holding plate and skillet tightly together, invert dumplings onto plate. Serve dumplings immediately, with dipping sauce.