(This can be made in advance and refrigerated until ready to use.) Grate the potatoes and set aside. Brown ground buffalo and onion in a large non-stick skillet, stirring to crumble. Add potatoes, spices and salt and pepper. Cook just briefly, until onions and potatoes are soft. Cool. (Winter tip: Spoon the buffalo mixture onto a jellyroll pan and stick outside for 15 minutes to cool.)
Mince the cilantro and green onions by hand or use a food processor. Combine in a bowl with vinegar and water; stir well and set aside.
Preheat oven to 400°F. Place two baking sheets in oven. Working with one wonton wrapper at a time (cover remaining wonton wrappers with a damp towel), spoon one tablespoon of filling into center of each wrapper. Moisten edges with water. Bring two opposite corners together and pinch edges to seal. Spray filled wrapper with olive oil or cooking spray and place on a wire rack. Repeat with all wrappers. Remove baking sheets from oven; immediately arrange empanadas in a single layer on hot baking sheets. Bake for 8 minutes or until golden, turning once. Serve immediately with cilantro sauce. Serves 12.