In a large bowl, combine the flaked salmon, breadcrumbs, green onions, and bell pepper.
Add the beaten egg, mayonnaise, and Dijon mustard to the bowl.
Season the mixture with salt and pepper to taste.
Mix all ingredients thoroughly until well combined.
Form the mixture into small patties, about 2 inches in diameter.
Heat oil in a skillet over medium heat.
Carefully place the patties in the hot oil, ensuring not to overcrowd the pan.
Fry for about 4-5 minutes on each side until golden brown and crispy.
Remove the croquettes from the skillet and place them on paper towels to drain excess oil.
Serve warm with lemon wedges on the side.