Scruncheons are small cubes (~1cm) of fat-back pork which have been cooked in a fry-pan on medium heat until the fat has come out and the cubes are crispy all the way through.
This may be used in a number of ways. One way is to use the oil to pan-fry a fish fillet, like fresh cod if you can get it. Another is to use the scruncheons as a topping for another food, like fish and brewis or delicious, sharp, peppery tasting, blue potatoes.
If fatback is used in a moist cooking process (i.e. boiled wih cabbage to improve flavour or on top of a dry meat like moose roast to moisten it) it is cut into thin strips that are attached to the rind like fingers, or the letter "E". These are discarded after cooking and are not the same thing as scruncheons. Many people will refer to vegetables that have not been cooked with fat back as tasting too "fresh", what they really mean is that it lacks salt.
Nobody ever said that Newfoundland cooking was low fat, low cholesterol or low sodium. The scruncheons are served in the oil that has been rendered from them, and this mixture is terribly salty.
This node has been renamed to the singular form against my wishes so many times that I have given up asking the hallowed E2 editors to return it to it's original state. Like mushy peas, this condiment/cooking ingredient is only ever referred to in the plural. So, if you were ordering in a restaurant that caters to expatriate Newfoundlanders, you might order salt cod and blue potatoes with a side of scruncheons (and you'd have a mighty fine meal there, too.)