Preheat the oven to broil.
In a nonstick skillet, brown the chorizo until cooked though. Drain on several paper towels and set aside.
In a 12-inch cast-iron skillet, layer the grated Cheddar, fontina, mozzarella and pepper Jack and top with the chorizo. Broil the fundido until bubbly and golden.
Char the tortillas directly over the cook-top flame until blistered.
Top the fundido with the cilantro and pickled jalapenos and serve with the charred tortillas.
This is a great recipe for using up the ends of different cheeses you might have in your fridge.