Combine parsley, salt, fennel, black pepper, garlic, Italian seasoning, minced onion, and red pepper flakes in a spice grinder or mortar and pestle. Grind until all seasonings are finely crushed.
Place pork in a large bowl and add seasoning mix. Mix with your hands until well combined. Roll into a log and slice into four 1/2-inch thick sausage patties.
Heat oil in a skillet over medium heat and cook sausage patties for 4 minutes. Turn patties and finish cooking for 4 more minutes. An instant-read thermometer inserted into the center should read at least 160 degrees F (73 degrees C).