Drain canned salmon and flake with a fork, removing large bones or skin if desired.
In a large bowl combine flaked salmon, beaten egg, mayonnaise, Dijon mustard, lemon zest and lemon juice.
Stir in minced shallot (or onion), chopped parsley, diced bell pepper (optional), salt and pepper.
Fold in 1/2 cup breadcrumbs until mixture holds together but remains moist; add more breadcrumbs if too wet.
Shape mixture into 4 large or 8 small patties, pressing firmly so they don’t fall apart.
Lightly coat each patty with additional breadcrumbs for extra crispiness.
Heat 2 tablespoons oil in a nonstick skillet over medium heat until shimmering.
Add patties without overcrowding and cook 3–4 minutes per side for small cakes or 4–6 minutes per side for large cakes, until golden brown.
Flip carefully once and press gently to promote even browning; add more oil if needed.
Transfer cooked cakes to a paper towel-lined plate to drain and rest 1–2 minutes before serving with lemon wedges or a dill-yogurt sauce.