1. In a large bowl, combine the flaked salmon, chopped onion, fresh parsley, breadcrumbs, eggs, mayonnaise, Dijon mustard, Old Bay seasoning, salt, and black pepper. Mix well until all ingredients are evenly incorporated.
2. Form the mixture into patties, approximately 3 inches in diameter. Place them on a baking sheet lined with parchment paper, then refrigerate for about 30 minutes. Chilling the patties will help them hold their shape during frying.
3. In a deep skillet or cast-iron pan, heat enough vegetable oil to cover the bottom of the pan by about 1/2 inch. Heat the oil over medium-high heat until it reaches 350°F (175°C).
4. Carefully place the chilled salmon patties into the hot oil, working in batches to avoid overcrowding the pan. Fry for about 3-4 minutes on each side, or until they are golden brown and crispy.
5. Once cooked, transfer the patties to a plate lined with paper towels to drain off any excess oil.
Serve the Southern Fried Salmon Patties hot, with a side of creamy coleslaw and tangy remoulade sauce. Enjoy their crispy exterior and tender, flavorful interior.