Combine masa harina with 1 3⁄4 cups hot water in a mixing bowl. Stir with a wooden spoon until mixture holds together, then knead with your hands until smooth, about 5 minutes. Cover with plastic wrap and set aside for 30 minutes.
Roll dough into 32 1 1⁄4" balls. To shape into even tortillas, flatten each ball by placing it between 2 heavy-duty plastic bags (freezer bags work well) and pressing it under a heavy pan until dough forms a tortilla with a 4" diameter. Carefully peel plastic from tortilla and place tortilla on a sheet of waxed paper. Repeat process, flattening remaining dough and laying tortillas on waxed paper as you go.
Spoon 1 heaping tbsp. empanada filling onto each tortilla, fold tortillas in half, enclosing filling, and pinch edges together to seal. Cover with plastic wrap until ready to cook. (Empanadas can be prepared up to this point and refrigerated overnight.)
Heat 1" oil in skillet over medium-high heat. When oil is hot but not smoking, add empanadas, a few at a time, and fry, turning once, until brown, about 1 minute per side. Drain on paper towels. Repeat with remaining empanadas. Serve with Salsa Negra, if you like.