In a large bowl, mix together the pigs feet, onion, cilantro, jalapeños and crema (or one of its stand-ins). Taste and season with salt if you think necessary. Cover and refrigerate until you're ready to serve.
Note: It's difficult to tell you just how many jars or pounds of pickled pigs feet to buy, since some will come cleaner (read: with less fat, cartilage and bone) than others. A dependable choice is Hormel's pickled pigs feet (though they won't include the pickled chiles and vegetables that you'll find in Mexican brands). Three 9-ounce jars will yield about 2 1/2 cups of cleaned, chopped pigs feet.
To clean the pigs feet, drain off the pickling liquid, then cutout or pull out any bones or hard pieces of cartilage and discard. Chop what remains into 1/2-inch bits.