In a large bowl combine flour, oil, salt and water. Mix well, and knead until the dough becomes homogeneous in texture (about 8-10 minutes). Cover and let stand for at least 30 minutes. Knead well again before making wrappers.
In a large bowl, combine all filling ingredients. Mix well, and adjust for seasoning with salt.
Give the dough a final knead. Prepare 1 inch dough balls. Take a ball and roll between your palms to spherical shape. Dust working board with dry flour. On the board gently flatten circles, cover with a bowl. Use a rolling pin to roll out each flattened circle into a wrapper.
NOTE: For well executed momos, it is essential that the middle portion of the wrapper be slightly thicker than the edges to ensure the structural integrity of dumplings during packing and steaming.
Hold the edges of the semi-flattened dough with one hand and with the other begin rolling the edges of the dough flour, swirling a bit at a time. Continue until the wrapper attains 3 inches in diameter (circular shape). Repeat with the remaining semi-flattened dough circles. Cover with bowl to prevent from drying.
For packing, hold wrapper on one palm, put one tablespoon of filling mixture and with the other hand bring all edges together to the center, making the pleats. Pinch and twist the pleats to ensure the absolute closure of the stuffed dumpling. This holds the key to a good tasting, juicy dumpling.
Heat up a steamer, oil the steamer rack well. This is critical because it will prevent dumplings from sticking. Arrange uncooked momos in the steamer. Close the lid, and allow steaming until the dumplings are cooked through; it takes about 20-25 minutes.
Take the dumplings out of the steamer, and immediately serve.