In a medium bowl combine coleslaw mix, red onion, and radishes; set aside. In a small saucepan combine vinegar, the 2 tablespoons water, the honey, 1/2 teaspoon salt, and the crushed red pepper. Bring to boiling. Pour vinegar mixture over cabbage mixture. Toss to combine. Transfer to a 1-quart jar; cover. Chill for at least 2 hours or up to 3 days before serving.
Discard jus from pork roast (or reserve it for another use). In a large skillet combine pork, 1/2 cup of the salsa, and the cumin. Bring to boiling; reduce heat. Simmer, uncovered, until nearly all the liquid has evaporated. Using a wooden spoon, break apart large pieces of pork until a shredded consistency is reached. Continue to cook until the pork is golden brown in places, stirring occasionally. Stir in enough of the remaining salsa to reach desired consistency. Remove from heat. Cool slightly.
In a large bowl combine masa harina, 1/2 teaspoon salt, and the cayenne pepper. Stir in the 2 1/4 cups warm water. If necessary, add enough additional water, 1 tablespoon at a time, to make a soft dough that can easily be shaped into a ball. Cover and let stand for 10 minutes.
Divide dough into 16 portions. Oil your hands with vegetable oil; shape dough portions into balls (balls should be golf ball size). Press your thumb into the center of a ball and mold into a bowl shape. Fill the dough bowl with 1 to 2 tablespoons of the pork filling and 1 tablespoon of the shredded cheese. Press dough over the filling to enclose. Pat the ball flat between your hands until 1/4 inch thick (about 4 inches in diameter). Repeat with the remaining dough and the remaining pork filling.
Preheat oven to 250 degrees F. Heat an oiled extra-large skillet or griddle over medium-high heat. Place four of the papusas in the skillet. Cook for 8 to 10 minutes or until golden brown in places and some cheese oozes out, turning once halfway through cooking time. Keep cooked papusas warm in the oven while cooking the remaining papusas. Serve with curtido. If desired, sprinkle with cilantro leaves.