Add the salmon, breadcrumbs, mayonnaise, dill, mustard, salt, seafood seasoning, pepper, egg, garlic, lemon zest and green onion to a bowl. Mix well. Scoop into mounded tablespoons, forming each into small discs.
Add 1 tablespoon each of olive oil and butter to a large nonstick skillet. Add half of the salmon cakes to the skillet. Cook until golden brown on the first side, 2 to 3 minutes. Carefully flip and cook until golden on the second side, an additional 2 minutes. Remove and repeat with the remaining oil, butter and salmon cakes.
Transfer the salmon cakes to a serving platter. Dollop each with a little sour cream and top with a dill frond. Serve warm.
