Drain salmon and place in medium sized bowl.
Combine salmon through egg in bowl, but use only half of bread crumbs.
Make the salmon mixture into 8 patties (for 4 yield), then cover both sides of patties with remaining breadcrumbs.
Heat frying oil in large frying pan. Place patties in pan and cook for 5 minutes, or until golden brown. Add more oil, flip patties, and cook on the other side for 5 more minutes.
Lightly steam the spinach and season with vinegar, or vinegar mixed with some of the dipping sauce.
Dipping Sauce: Combine 1/2 c. plain, Greek style or regular yogurt with 1 Tbsp. horseradish. Add more to taste. (Could also use plain ketchup, tartar sauce, or lemon juice for seasoning the patties.)