For the green chorizo, broil peppers, tomatillos and garlic to char evenly. Place peppers in bowl and cover, cool to handle, then peel, stem and seed peppers. Peel garlic. Place the peppers, tomatillos, garlic, parsley and cilantro in a food processor.
In a small skillet over medium heat, toast the pepitas, cumin, peppercorn and oregano a minute or 2, then place in spice mill with sesame seeds and grind.
Place pork in a bowl and add salt, vinegar, green paste and spice blend. Mix well, then cover and refrigerate. Make the sausage and refrigerate at least 1`hour or preferably overnight before cooking.
For the queso sauce, add the oil, 2 turns of the pan, to a saucepot over medium heat, then add onions, garlic and salt and cook to soften, do not brown, add about ½ cup water to prevent browning as the onions begin to breakdown, and let it absorb. Add crema or milk and cream cheese to the pot along with the cheeses, a few handfuls at a time, while stirring to guard the cheese from scorching. Once hot, remove from heat and cover.
For the skillet nachos, heat a cast-iron skillet over medium-high heat and add oil, 2 turns of the pan, add the green chorizo and brown and crumble the meat, add stock and let it absorb. Top and fill the skillet with corn chips, top the chips with the cheese sauce. Broil to heat chips and brown sauce a bit. Serve right from the skillet and garnish with scallions, cilantro and pickled jalapeño slices.