Place 1/2 of the salmon, breadcrumbs, egg white, spring onion, roasted red pepper, parsley, 1 1/2 teaspoons baharat and salt in a food processor; blend until combined.
Transfer blended mixture to a bowl. Chop remaining salmon into 1cm pieces and add to the bowl. Mix well until soft. Shape into four salmon cakes.
Preheat grill. Arrange salmon cakes on a foil-lined baking tray.
Grill salmon cakes on top rack, turning once, until cooked through, 14 to 18 minutes.
For the aioli; Mix mayonnaise, garlic, lemon juice, lemon zest and remaining 1/4 teaspoon baharat in a small bowl.
Garnish salmon cakes with black pepper and serve with aioli.