For the pickled cabbage: Combine the vegetables in a large bowl. In a medium saucepan, add the vinegar, water, spices, brown sugar and salt and bring to a boil. Pour the hot pickling liquid over the vegetables. Mix the ingredients well and let stand for at least 24 hours before serving, stirring occasionally. This mixture will keep for 2 to 3 weeks covered in the refrigerator.
For the pork filling: Season the pork with the salt and pepper and place in a medium saucepan. Add enough water to cover by 2-inches, about 6 cups. Bring to a simmer and partially cover the pot; cook until the meat is very tender and almost all of the liquid has evaporated, about 3 hours. Uncover the pork and let it slightly pan fry in its own fat, stirring, until golden brown.
Meanwhile, combine the tomatoes, onion, garlic, jalapeno, oregano and cinnamon in a blender. Puree until smooth. Add the tomato mixture to the pork in the saucepan and stir to loosen any browned bits from the bottom of the pan. Lower the heat and simmer for another 30 minutes, or until pork is falling apart and most of the liquid has reduced from the sauce. The pork mixture should be very thick. Set aside to cool while you prepare the masa dough. (This will yield more pork than you need for this recipe but any leftover can be frozen and/or used in other recipes. It makes a great filling for tacos, burritos, quesadillas or enchiladas and also works well as a sandwich filling when mixed with a tangy barbecue sauce.)
For the dough: In a bowl, combine the masa harina with the warm water and salt mix until soft dough forms. Let stand for 20 to 30 minutes. Stir in up to a 1/4 cup of cold water, until the dough become soft but not sticky. Divide the dough into 16 golf ball size pieces. Keep the dough covered as you work.
To form a pupusa: Rub the palm of your hands with a little olive oil. While holding of the dough balls in 1 hand, press the thumb of the other hand in the middle of the ball of dough to form an indentation, then turning the dough, begin to flatten it with your fingertips into a 4-inch concave disk resembling a small bowl. In the center of the disk add 2 tablespoons of the pork and 1/2 tablespoon of the shredded cheese. Bring the edges of the dough together over the filling and squeeze to form a seal. Working gently, press the dough into a flattened disk, flattening the dough middle and edges to form a thick pancake shape about 4-inches in diameter. Repeat with the remaining dough and filling.
Lightly rub the pupusas with oil and place them on a heated, greased griddle over medium-high heat. Cook each side until golden brown in spots and slightly puffy, 3 to 4 minutes per side. Serve hot, with a serving of the pickled cabbage on the side.