Grilled Salmon Cakes with Lemon Mayonnaise

6 green onion s (2 minced, 4 cut into 4-inch lengths)

1 tablespoon fresh lemon juice

2 teaspoons grated lemon peel

1/4 cup (packed) chopped fresh Italian parsley

1 

1/4 pounds skinless salmon fillets, cut into 1-inch cubes

2 tablespoons Dijon mustard

1/2 cup panko (Japanese breadcrumbs) or fresh breadcrumbs made from crustless French bread

3/4 teaspoon salt

3/4 teaspoon ground black pepper

Olive oil